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/* Generic definitions */
/* Assertions (useful to generate conditional code) */
/* Current type and class (and size, if applicable) */
/* Value methods */
/* Interfaces (keys) */
/* Interfaces (values) */
/* Abstract implementations (keys) */
/* Abstract implementations (values) */
/* Static containers (keys) */
/* Static containers (values) */
/* Implementations */
/* Synchronized wrappers */
/* Unmodifiable wrappers */
/* Other wrappers */
/* Methods (keys) */
/* Methods (values) */
/* Methods (keys/values) */
/* Methods that have special names depending on keys (but the special names depend on values) */
/* Equality */
/* Object/Reference-only definitions (keys) */
/* Object/Reference-only definitions (values) */
/*
* Copyright (C) 2002-2015 Sebastiano Vigna
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*
*
* For the sorting and binary search code:
*
* Copyright (C) 1999 CERN - European Organization for Nuclear Research.
*
* Permission to use, copy, modify, distribute and sell this software and
* its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appear in all copies and that
* both that copyright notice and this permission notice appear in
* supporting documentation. CERN makes no representations about the
* suitability of this software for any purpose. It is provided "as is"
* without expressed or implied warranty.
*/
package it.unimi.dsi.fastutil.objects;
import it.unimi.dsi.fastutil.Arrays;
import it.unimi.dsi.fastutil.Hash;
import java.util.Random;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.RecursiveAction;
import it.unimi.dsi.fastutil.ints.IntArrays;
import java.util.Comparator;
/** A class providing static methods and objects that do useful things with type-specific arrays.
*
* In particular, the ensureCapacity(), grow(), trim() and setLength() methods allow to handle arrays much like array lists. This can be very useful
* when efficiency (or syntactic simplicity) reasons make array lists unsuitable.
*
* Warning: if your array is not of type {@code Object[]}, {@link #ensureCapacity(Object[],int,int)} and {@link #grow(Object[],int,int)} will use
* {@linkplain java.lang.reflect.Array#newInstance(Class,int) reflection} to preserve your array type. Reflection is significantly slower than using new. This phenomenon is
* particularly evident in the first growth phases of an array reallocated with doubling (or similar) logic.
*
*
Sorting
*
* There are several sorting methods available. The main theme is that of letting you choose the sorting algorithm you prefer (i.e., trading stability of mergesort for no memory allocation in
* quicksort). Several algorithms provide a parallel version, that will use the {@linkplain Runtime#availableProcessors() number of cores available}.
*
*
All comparison-based algorithm have an implementation based on a type-specific comparator.
*
*
If you are fine with not knowing exactly which algorithm will be run (in particular, not knowing exactly whether a support array will be allocated), the dual-pivot parallel sorts in
* {@link java.util.Arrays} are about 50% faster than the classical single-pivot implementation used here.
*
*
In any case, if sorting time is important I suggest that you benchmark your sorting load with your data distribution and on your architecture.
*
* @see java.util.Arrays */
public class ObjectArrays {
private ObjectArrays() {}
/** A static, final, empty array. */
public final static Object[] EMPTY_ARRAY = {};
/** Creates a new array using a the given one as prototype.
*
*
This method returns a new array of the given length whose element are of the same class as of those of prototype. In case of an empty array, it tries to return
* {@link #EMPTY_ARRAY}, if possible.
*
* @param prototype an array that will be used to type the new one.
* @param length the length of the new array.
* @return a new array of given type and length. */
@SuppressWarnings("unchecked")
private static K[] newArray( final K[] prototype, final int length ) {
final Class klass = prototype.getClass();
if ( klass == Object[].class ) return (K[])( length == 0 ? EMPTY_ARRAY : new Object[ length ] );
return (K[])java.lang.reflect.Array.newInstance( klass.getComponentType(), length );
}
/** Ensures that an array can contain the given number of entries.
*
* If you cannot foresee whether this array will need again to be enlarged, you should probably use grow() instead.
*
* @param array an array.
* @param length the new minimum length for this array.
* @return array, if it contains length entries or more; otherwise, an array with length entries whose first array.length entries are the same
* as those of array. */
public static K[] ensureCapacity( final K[] array, final int length ) {
if ( length > array.length ) {
final K t[] =
newArray( array, length );
System.arraycopy( array, 0, t, 0, array.length );
return t;
}
return array;
}
/** Ensures that an array can contain the given number of entries, preserving just a part of the array.
*
* @param array an array.
* @param length the new minimum length for this array.
* @param preserve the number of elements of the array that must be preserved in case a new allocation is necessary.
* @return array, if it can contain length entries or more; otherwise, an array with length entries whose first preserve entries are the same as
* those of array. */
public static K[] ensureCapacity( final K[] array, final int length, final int preserve ) {
if ( length > array.length ) {
final K t[] =
newArray( array, length );
System.arraycopy( array, 0, t, 0, preserve );
return t;
}
return array;
}
/** Grows the given array to the maximum between the given length and the current length multiplied by two, provided that the given length is larger than the current length.
*
* If you want complete control on the array growth, you should probably use ensureCapacity() instead.
*
* @param array an array.
* @param length the new minimum length for this array.
* @return array, if it can contain length entries; otherwise, an array with max(length,array.length/φ) entries whose first
* array.length entries are the same as those of array. */
public static K[] grow( final K[] array, final int length ) {
if ( length > array.length ) {
final int newLength = (int)Math.max( Math.min( 2L * array.length, Arrays.MAX_ARRAY_SIZE ), length );
final K t[] =
newArray( array, newLength );
System.arraycopy( array, 0, t, 0, array.length );
return t;
}
return array;
}
/** Grows the given array to the maximum between the given length and the current length multiplied by two, provided that the given length is larger than the current length, preserving just a part
* of the array.
*
* If you want complete control on the array growth, you should probably use ensureCapacity() instead.
*
* @param array an array.
* @param length the new minimum length for this array.
* @param preserve the number of elements of the array that must be preserved in case a new allocation is necessary.
* @return array, if it can contain length entries; otherwise, an array with max(length,array.length/φ) entries whose first
* preserve entries are the same as those of array. */
public static K[] grow( final K[] array, final int length, final int preserve ) {
if ( length > array.length ) {
final int newLength = (int)Math.max( Math.min( 2L * array.length, Arrays.MAX_ARRAY_SIZE ), length );
final K t[] =
newArray( array, newLength );
System.arraycopy( array, 0, t, 0, preserve );
return t;
}
return array;
}
/** Trims the given array to the given length.
*
* @param array an array.
* @param length the new maximum length for the array.
* @return array, if it contains length entries or less; otherwise, an array with length entries whose entries are the same as the first length
* entries of array. */
public static K[] trim( final K[] array, final int length ) {
if ( length >= array.length ) return array;
final K t[] =
newArray( array, length );
System.arraycopy( array, 0, t, 0, length );
return t;
}
/** Sets the length of the given array.
*
* @param array an array.
* @param length the new length for the array.
* @return array, if it contains exactly length entries; otherwise, if it contains more than length entries, an array with length
* entries whose entries are the same as the first length entries of array; otherwise, an array with length entries whose first array.length
* entries are the same as those of array. */
public static K[] setLength( final K[] array, final int length ) {
if ( length == array.length ) return array;
if ( length < array.length ) return trim( array, length );
return ensureCapacity( array, length );
}
/** Returns a copy of a portion of an array.
*
* @param array an array.
* @param offset the first element to copy.
* @param length the number of elements to copy.
* @return a new array containing length elements of array starting at offset. */
public static K[] copy( final K[] array, final int offset, final int length ) {
ensureOffsetLength( array, offset, length );
final K[] a =
newArray( array, length );
System.arraycopy( array, offset, a, 0, length );
return a;
}
/** Returns a copy of an array.
*
* @param array an array.
* @return a copy of array. */
public static K[] copy( final K[] array ) {
return array.clone();
}
/** Fills the given array with the given value.
*
* @param array an array.
* @param value the new value for all elements of the array.
* @deprecated Please use the corresponding {@link java.util.Arrays} method. */
@Deprecated
public static void fill( final K[] array, final K value ) {
int i = array.length;
while ( i-- != 0 )
array[ i ] = value;
}
/** Fills a portion of the given array with the given value.
*
* @param array an array.
* @param from the starting index of the portion to fill (inclusive).
* @param to the end index of the portion to fill (exclusive).
* @param value the new value for all elements of the specified portion of the array.
* @deprecated Please use the corresponding {@link java.util.Arrays} method. */
@Deprecated
public static void fill( final K[] array, final int from, int to, final K value ) {
ensureFromTo( array, from, to );
if ( from == 0 ) while ( to-- != 0 )
array[ to ] = value;
else for ( int i = from; i < to; i++ )
array[ i ] = value;
}
/** Returns true if the two arrays are elementwise equal.
*
* @param a1 an array.
* @param a2 another array.
* @return true if the two arrays are of the same length, and their elements are equal.
* @deprecated Please use the corresponding {@link java.util.Arrays} method, which is intrinsified in recent JVMs. */
@Deprecated
public static boolean equals( final K[] a1, final K a2[] ) {
int i = a1.length;
if ( i != a2.length ) return false;
while ( i-- != 0 )
if ( !( ( a1[ i ] ) == null ? ( a2[ i ] ) == null : ( a1[ i ] ).equals( a2[ i ] ) ) ) return false;
return true;
}
/** Ensures that a range given by its first (inclusive) and last (exclusive) elements fits an array.
*
* This method may be used whenever an array range check is needed.
*
* @param a an array.
* @param from a start index (inclusive).
* @param to an end index (exclusive).
* @throws IllegalArgumentException if from is greater than to.
* @throws ArrayIndexOutOfBoundsException if from or to are greater than the array length or negative. */
public static void ensureFromTo( final K[] a, final int from, final int to ) {
Arrays.ensureFromTo( a.length, from, to );
}
/** Ensures that a range given by an offset and a length fits an array.
*
* This method may be used whenever an array range check is needed.
*
* @param a an array.
* @param offset a start index.
* @param length a length (the number of elements in the range).
* @throws IllegalArgumentException if length is negative.
* @throws ArrayIndexOutOfBoundsException if offset is negative or offset+length is greater than the array length. */
public static void ensureOffsetLength( final K[] a, final int offset, final int length ) {
Arrays.ensureOffsetLength( a.length, offset, length );
}
/** Ensures that two arrays are of the same length.
*
* @param a an array.
* @param b another array.
* @throws IllegalArgumentException if the two argument arrays are not of the same length. */
public static void ensureSameLength( final K[] a, final K[] b ) {
if ( a.length != b.length ) throw new IllegalArgumentException( "Array size mismatch: " + a.length + " != " + b.length );
}
private static final int QUICKSORT_NO_REC = 16;
private static final int PARALLEL_QUICKSORT_NO_FORK = 8192;
private static final int QUICKSORT_MEDIAN_OF_9 = 128;
private static final int MERGESORT_NO_REC = 16;
/** Swaps two elements of an anrray.
*
* @param x an array.
* @param a a position in {@code x}.
* @param b another position in {@code x}. */
public static void swap( final K x[], final int a, final int b ) {
final K t = x[ a ];
x[ a ] = x[ b ];
x[ b ] = t;
}
/** Swaps two sequences of elements of an array.
*
* @param x an array.
* @param a a position in {@code x}.
* @param b another position in {@code x}.
* @param n the number of elements to exchange starting at {@code a} and {@code b}. */
public static void swap( final K[] x, int a, int b, final int n ) {
for ( int i = 0; i < n; i++, a++, b++ )
swap( x, a, b );
}
private static int med3( final K x[], final int a, final int b, final int c, Comparator comp ) {
final int ab = comp.compare( x[ a ], x[ b ] );
final int ac = comp.compare( x[ a ], x[ c ] );
final int bc = comp.compare( x[ b ], x[ c ] );
return ( ab < 0 ?
( bc < 0 ? b : ac < 0 ? c : a ) :
( bc > 0 ? b : ac > 0 ? c : a ) );
}
private static void selectionSort( final K[] a, final int from, final int to, final Comparator comp ) {
for ( int i = from; i < to - 1; i++ ) {
int m = i;
for ( int j = i + 1; j < to; j++ )
if ( comp.compare( a[ j ], a[ m ] ) < 0 ) m = j;
if ( m != i ) {
final K u = a[ i ];
a[ i ] = a[ m ];
a[ m ] = u;
}
}
}
private static void insertionSort( final K[] a, final int from, final int to, final Comparator comp ) {
for ( int i = from; ++i < to; ) {
K t = a[ i ];
int j = i;
for ( K u = a[ j - 1 ]; comp.compare( t, u ) < 0; u = a[ --j - 1 ] ) {
a[ j ] = u;
if ( from == j - 1 ) {
--j;
break;
}
}
a[ j ] = t;
}
}
/** Sorts the specified range of elements according to the order induced by the specified comparator using quicksort.
*
* The sorting algorithm is a tuned quicksort adapted from Jon L. Bentley and M. Douglas McIlroy, “Engineering a Sort Function”, Software: Practice and Experience, 23(11),
* pages 1249−1265, 1993.
*
*
Note that this implementation does not allocate any object, contrarily to the implementation used to sort primitive types in {@link java.util.Arrays}, which switches to mergesort on large
* inputs.
*
* @param x the array to be sorted.
* @param from the index of the first element (inclusive) to be sorted.
* @param to the index of the last element (exclusive) to be sorted.
* @param comp the comparator to determine the sorting order. */
public static void quickSort( final K[] x, final int from, final int to, final Comparator comp ) {
final int len = to - from;
// Selection sort on smallest arrays
if ( len < QUICKSORT_NO_REC ) {
selectionSort( x, from, to, comp );
return;
}
// Choose a partition element, v
int m = from + len / 2;
int l = from;
int n = to - 1;
if ( len > QUICKSORT_MEDIAN_OF_9 ) { // Big arrays, pseudomedian of 9
int s = len / 8;
l = med3( x, l, l + s, l + 2 * s, comp );
m = med3( x, m - s, m, m + s, comp );
n = med3( x, n - 2 * s, n - s, n, comp );
}
m = med3( x, l, m, n, comp ); // Mid-size, med of 3
final K v = x[ m ];
// Establish Invariant: v* (v)* v*
int a = from, b = a, c = to - 1, d = c;
while ( true ) {
int comparison;
while ( b <= c && ( comparison = comp.compare( x[ b ], v ) ) <= 0 ) {
if ( comparison == 0 ) swap( x, a++, b );
b++;
}
while ( c >= b && ( comparison = comp.compare( x[ c ], v ) ) >= 0 ) {
if ( comparison == 0 ) swap( x, c, d-- );
c--;
}
if ( b > c ) break;
swap( x, b++, c-- );
}
// Swap partition elements back to middle
int s;
s = Math.min( a - from, b - a );
swap( x, from, b - s, s );
s = Math.min( d - c, to - d - 1 );
swap( x, b, to - s, s );
// Recursively sort non-partition-elements
if ( ( s = b - a ) > 1 ) quickSort( x, from, from + s, comp );
if ( ( s = d - c ) > 1 ) quickSort( x, to - s, to, comp );
}
/** Sorts an array according to the order induced by the specified comparator using quicksort.
*
* The sorting algorithm is a tuned quicksort adapted from Jon L. Bentley and M. Douglas McIlroy, “Engineering a Sort Function”, Software: Practice and Experience, 23(11),
* pages 1249−1265, 1993.
*
*
Note that this implementation does not allocate any object, contrarily to the implementation used to sort primitive types in {@link java.util.Arrays}, which switches to mergesort on large
* inputs.
*
* @param x the array to be sorted.
* @param comp the comparator to determine the sorting order. */
public static void quickSort( final K[] x, final Comparator comp ) {
quickSort( x, 0, x.length, comp );
}
protected static class ForkJoinQuickSortComp extends RecursiveAction {
private static final long serialVersionUID = 1L;
private final int from;
private final int to;
private final K[] x;
private final Comparator comp;
public ForkJoinQuickSortComp( final K[] x, final int from, final int to, final Comparator comp ) {
this.from = from;
this.to = to;
this.x = x;
this.comp = comp;
}
@Override
protected void compute() {
final K[] x = this.x;
final int len = to - from;
if ( len < PARALLEL_QUICKSORT_NO_FORK ) {
quickSort( x, from, to, comp );
return;
}
// Choose a partition element, v
int m = from + len / 2;
int l = from;
int n = to - 1;
int s = len / 8;
l = med3( x, l, l + s, l + 2 * s );
m = med3( x, m - s, m, m + s );
n = med3( x, n - 2 * s, n - s, n );
m = med3( x, l, m, n );
final K v = x[ m ];
// Establish Invariant: v* (v)* v*
int a = from, b = a, c = to - 1, d = c;
while ( true ) {
int comparison;
while ( b <= c && ( comparison = comp.compare( x[ b ], v ) ) <= 0 ) {
if ( comparison == 0 ) swap( x, a++, b );
b++;
}
while ( c >= b && ( comparison = comp.compare( x[ c ], v ) ) >= 0 ) {
if ( comparison == 0 ) swap( x, c, d-- );
c--;
}
if ( b > c ) break;
swap( x, b++, c-- );
}
// Swap partition elements back to middle
int t;
s = Math.min( a - from, b - a );
swap( x, from, b - s, s );
s = Math.min( d - c, to - d - 1 );
swap( x, b, to - s, s );
// Recursively sort non-partition-elements
s = b - a;
t = d - c;
if ( s > 1 && t > 1 ) invokeAll( new ForkJoinQuickSortComp( x, from, from + s, comp ), new ForkJoinQuickSortComp( x, to - t, to, comp ) );
else if ( s > 1 ) invokeAll( new ForkJoinQuickSortComp( x, from, from + s, comp ) );
else invokeAll( new ForkJoinQuickSortComp( x, to - t, to, comp ) );
}
}
/** Sorts the specified range of elements according to the order induced by the specified comparator using a parallel quicksort.
*
* The sorting algorithm is a tuned quicksort adapted from Jon L. Bentley and M. Douglas McIlroy, “Engineering a Sort Function”, Software: Practice and Experience, 23(11),
* pages 1249−1265, 1993.
*
*
This implementation uses a {@link ForkJoinPool} executor service with {@link Runtime#availableProcessors()} parallel threads.
*
* @param x the array to be sorted.
* @param from the index of the first element (inclusive) to be sorted.
* @param to the index of the last element (exclusive) to be sorted.
* @param comp the comparator to determine the sorting order. */
public static void parallelQuickSort( final K[] x, final int from, final int to, final Comparator comp ) {
final ForkJoinPool pool = new ForkJoinPool( Runtime.getRuntime().availableProcessors() );
pool.invoke( new ForkJoinQuickSortComp( x, from, to, comp ) );
pool.shutdown();
}
/** Sorts an array according to the order induced by the specified comparator using a parallel quicksort.
*
* The sorting algorithm is a tuned quicksort adapted from Jon L. Bentley and M. Douglas McIlroy, “Engineering a Sort Function”, Software: Practice and Experience, 23(11),
* pages 1249−1265, 1993.
*
*
This implementation uses a {@link ForkJoinPool} executor service with {@link Runtime#availableProcessors()} parallel threads.
*
* @param x the array to be sorted.
* @param comp the comparator to determine the sorting order. */
public static void parallelQuickSort( final K[] x, final Comparator comp ) {
parallelQuickSort( x, 0, x.length, comp );
}
@SuppressWarnings("unchecked")
private static int med3( final K x[], final int a, final int b, final int c ) {
final int ab = ( ( (Comparable)( x[ a ] ) ).compareTo( x[ b ] ) );
final int ac = ( ( (Comparable)( x[ a ] ) ).compareTo( x[ c ] ) );
final int bc = ( ( (Comparable)( x[ b ] ) ).compareTo( x[ c ] ) );
return ( ab < 0 ?
( bc < 0 ? b : ac < 0 ? c : a ) :
( bc > 0 ? b : ac > 0 ? c : a ) );
}
@SuppressWarnings("unchecked")
private static void selectionSort( final K[] a, final int from, final int to ) {
for ( int i = from; i < to - 1; i++ ) {
int m = i;
for ( int j = i + 1; j < to; j++ )
if ( ( ( (Comparable)( a[ j ] ) ).compareTo( a[ m ] ) < 0 ) ) m = j;
if ( m != i ) {
final K u = a[ i ];
a[ i ] = a[ m ];
a[ m ] = u;
}
}
}
@SuppressWarnings("unchecked")
private static void insertionSort( final K[] a, final int from, final int to ) {
for ( int i = from; ++i < to; ) {
K t = a[ i ];
int j = i;
for ( K u = a[ j - 1 ]; ( ( (Comparable)( t ) ).compareTo( u ) < 0 ); u = a[ --j - 1 ] ) {
a[ j ] = u;
if ( from == j - 1 ) {
--j;
break;
}
}
a[ j ] = t;
}
}
/** Sorts the specified range of elements according to the natural ascending order using quicksort.
*
* The sorting algorithm is a tuned quicksort adapted from Jon L. Bentley and M. Douglas McIlroy, “Engineering a Sort Function”, Software: Practice and Experience, 23(11),
* pages 1249−1265, 1993.
*
*
Note that this implementation does not allocate any object, contrarily to the implementation used to sort primitive types in {@link java.util.Arrays}, which switches to mergesort on large
* inputs.
*
* @param x the array to be sorted.
* @param from the index of the first element (inclusive) to be sorted.
* @param to the index of the last element (exclusive) to be sorted. */
@SuppressWarnings("unchecked")
public static void quickSort( final K[] x, final int from, final int to ) {
final int len = to - from;
// Selection sort on smallest arrays
if ( len < QUICKSORT_NO_REC ) {
selectionSort( x, from, to );
return;
}
// Choose a partition element, v
int m = from + len / 2;
int l = from;
int n = to - 1;
if ( len > QUICKSORT_MEDIAN_OF_9 ) { // Big arrays, pseudomedian of 9
int s = len / 8;
l = med3( x, l, l + s, l + 2 * s );
m = med3( x, m - s, m, m + s );
n = med3( x, n - 2 * s, n - s, n );
}
m = med3( x, l, m, n ); // Mid-size, med of 3
final K v = x[ m ];
// Establish Invariant: v* (v)* v*
int a = from, b = a, c = to - 1, d = c;
while ( true ) {
int comparison;
while ( b <= c && ( comparison = ( ( (Comparable)( x[ b ] ) ).compareTo( v ) ) ) <= 0 ) {
if ( comparison == 0 ) swap( x, a++, b );
b++;
}
while ( c >= b && ( comparison = ( ( (Comparable)( x[ c ] ) ).compareTo( v ) ) ) >= 0 ) {
if ( comparison == 0 ) swap( x, c, d-- );
c--;
}
if ( b > c ) break;
swap( x, b++, c-- );
}
// Swap partition elements back to middle
int s;
s = Math.min( a - from, b - a );
swap( x, from, b - s, s );
s = Math.min( d - c, to - d - 1 );
swap( x, b, to - s, s );
// Recursively sort non-partition-elements
if ( ( s = b - a ) > 1 ) quickSort( x, from, from + s );
if ( ( s = d - c ) > 1 ) quickSort( x, to - s, to );
}
/** Sorts an array according to the natural ascending order using quicksort.
*
* The sorting algorithm is a tuned quicksort adapted from Jon L. Bentley and M. Douglas McIlroy, “Engineering a Sort Function”, Software: Practice and Experience, 23(11),
* pages 1249−1265, 1993.
*
*
Note that this implementation does not allocate any object, contrarily to the implementation used to sort primitive types in {@link java.util.Arrays}, which switches to mergesort on large
* inputs.
*
* @param x the array to be sorted. */
public static void quickSort( final K[] x ) {
quickSort( x, 0, x.length );
}
protected static class ForkJoinQuickSort extends RecursiveAction {
private static final long serialVersionUID = 1L;
private final int from;
private final int to;
private final K[] x;
public ForkJoinQuickSort( final K[] x, final int from, final int to ) {
this.from = from;
this.to = to;
this.x = x;
}
@Override
@SuppressWarnings("unchecked")
protected void compute() {
final K[] x = this.x;
final int len = to - from;
if ( len < PARALLEL_QUICKSORT_NO_FORK ) {
quickSort( x, from, to );
return;
}
// Choose a partition element, v
int m = from + len / 2;
int l = from;
int n = to - 1;
int s = len / 8;
l = med3( x, l, l + s, l + 2 * s );
m = med3( x, m - s, m, m + s );
n = med3( x, n - 2 * s, n - s, n );
m = med3( x, l, m, n );
final K v = x[ m ];
// Establish Invariant: v* (v)* v*
int a = from, b = a, c = to - 1, d = c;
while ( true ) {
int comparison;
while ( b <= c && ( comparison = ( ( (Comparable)( x[ b ] ) ).compareTo( v ) ) ) <= 0 ) {
if ( comparison == 0 ) swap( x, a++, b );
b++;
}
while ( c >= b && ( comparison = ( ( (Comparable)( x[ c ] ) ).compareTo( v ) ) ) >= 0 ) {
if ( comparison == 0 ) swap( x, c, d-- );
c--;
}
if ( b > c ) break;
swap( x, b++, c-- );
}
// Swap partition elements back to middle
int t;
s = Math.min( a - from, b - a );
swap( x, from, b - s, s );
s = Math.min( d - c, to - d - 1 );
swap( x, b, to - s, s );
// Recursively sort non-partition-elements
s = b - a;
t = d - c;
if ( s > 1 && t > 1 ) invokeAll( new ForkJoinQuickSort( x, from, from + s ), new ForkJoinQuickSort( x, to - t, to ) );
else if ( s > 1 ) invokeAll( new ForkJoinQuickSort( x, from, from + s ) );
else invokeAll( new ForkJoinQuickSort( x, to - t, to ) );
}
}
/** Sorts the specified range of elements according to the natural ascending order using a parallel quicksort.
*
* The sorting algorithm is a tuned quicksort adapted from Jon L. Bentley and M. Douglas McIlroy, “Engineering a Sort Function”, Software: Practice and Experience, 23(11),
* pages 1249−1265, 1993.
*
*
This implementation uses a {@link ForkJoinPool} executor service with {@link Runtime#availableProcessors()} parallel threads.
*
* @param x the array to be sorted.
* @param from the index of the first element (inclusive) to be sorted.
* @param to the index of the last element (exclusive) to be sorted. */
public static void parallelQuickSort( final K[] x, final int from, final int to ) {
final ForkJoinPool pool = new ForkJoinPool( Runtime.getRuntime().availableProcessors() );
pool.invoke( new ForkJoinQuickSort( x, from, to ) );
pool.shutdown();
}
/** Sorts an array according to the natural ascending order using a parallel quicksort.
*
* The sorting algorithm is a tuned quicksort adapted from Jon L. Bentley and M. Douglas McIlroy, “Engineering a Sort Function”, Software: Practice and Experience, 23(11),
* pages 1249−1265, 1993.
*
*
This implementation uses a {@link ForkJoinPool} executor service with {@link Runtime#availableProcessors()} parallel threads.
*
* @param x the array to be sorted. */
public static void parallelQuickSort( final K[] x ) {
parallelQuickSort( x, 0, x.length );
}
@SuppressWarnings("unchecked")
private static int med3Indirect( final int perm[], final K x[], final int a, final int b, final int c ) {
final K aa = x[ perm[ a ] ];
final K bb = x[ perm[ b ] ];
final K cc = x[ perm[ c ] ];
final int ab = ( ( (Comparable)( aa ) ).compareTo( bb ) );
final int ac = ( ( (Comparable)( aa ) ).compareTo( cc ) );
final int bc = ( ( (Comparable)( bb ) ).compareTo( cc ) );
return ( ab < 0 ?
( bc < 0 ? b : ac < 0 ? c : a ) :
( bc > 0 ? b : ac > 0 ? c : a ) );
}
@SuppressWarnings("unchecked")
private static void insertionSortIndirect( final int[] perm, final K[] a, final int from, final int to ) {
for ( int i = from; ++i < to; ) {
int t = perm[ i ];
int j = i;
for ( int u = perm[ j - 1 ]; ( ( (Comparable)( a[ t ] ) ).compareTo( a[ u ] ) < 0 ); u = perm[ --j - 1 ] ) {
perm[ j ] = u;
if ( from == j - 1 ) {
--j;
break;
}
}
perm[ j ] = t;
}
}
/** Sorts the specified range of elements according to the natural ascending order using indirect quicksort.
*
* The sorting algorithm is a tuned quicksort adapted from Jon L. Bentley and M. Douglas McIlroy, “Engineering a Sort Function”, Software: Practice and Experience, 23(11),
* pages 1249−1265, 1993.
*
*
This method implement an indirect sort. The elements of perm (which must be exactly the numbers in the interval [0..perm.length)) will be permuted so that
* x[ perm[ i ] ] ≤ x[ perm[ i + 1 ] ].
*
*
Note that this implementation does not allocate any object, contrarily to the implementation used to sort primitive types in {@link java.util.Arrays}, which switches to mergesort on large
* inputs.
*
* @param perm a permutation array indexing {@code x}.
* @param x the array to be sorted.
* @param from the index of the first element (inclusive) to be sorted.
* @param to the index of the last element (exclusive) to be sorted. */
@SuppressWarnings("unchecked")
public static void quickSortIndirect( final int[] perm, final K[] x, final int from, final int to ) {
final int len = to - from;
// Selection sort on smallest arrays
if ( len < QUICKSORT_NO_REC ) {
insertionSortIndirect( perm, x, from, to );
return;
}
// Choose a partition element, v
int m = from + len / 2;
int l = from;
int n = to - 1;
if ( len > QUICKSORT_MEDIAN_OF_9 ) { // Big arrays, pseudomedian of 9
int s = len / 8;
l = med3Indirect( perm, x, l, l + s, l + 2 * s );
m = med3Indirect( perm, x, m - s, m, m + s );
n = med3Indirect( perm, x, n - 2 * s, n - s, n );
}
m = med3Indirect( perm, x, l, m, n ); // Mid-size, med of 3
final K v = x[ perm[ m ] ];
// Establish Invariant: v* (v)* v*
int a = from, b = a, c = to - 1, d = c;
while ( true ) {
int comparison;
while ( b <= c && ( comparison = ( ( (Comparable)( x[ perm[ b ] ] ) ).compareTo( v ) ) ) <= 0 ) {
if ( comparison == 0 ) IntArrays.swap( perm, a++, b );
b++;
}
while ( c >= b && ( comparison = ( ( (Comparable)( x[ perm[ c ] ] ) ).compareTo( v ) ) ) >= 0 ) {
if ( comparison == 0 ) IntArrays.swap( perm, c, d-- );
c--;
}
if ( b > c ) break;
IntArrays.swap( perm, b++, c-- );
}
// Swap partition elements back to middle
int s;
s = Math.min( a - from, b - a );
IntArrays.swap( perm, from, b - s, s );
s = Math.min( d - c, to - d - 1 );
IntArrays.swap( perm, b, to - s, s );
// Recursively sort non-partition-elements
if ( ( s = b - a ) > 1 ) quickSortIndirect( perm, x, from, from + s );
if ( ( s = d - c ) > 1 ) quickSortIndirect( perm, x, to - s, to );
}
/** Sorts an array according to the natural ascending order using indirect quicksort.
*
* The sorting algorithm is a tuned quicksort adapted from Jon L. Bentley and M. Douglas McIlroy, “Engineering a Sort Function”, Software: Practice and Experience, 23(11),
* pages 1249−1265, 1993.
*
*
This method implement an indirect sort. The elements of perm (which must be exactly the numbers in the interval [0..perm.length)) will be permuted so that
* x[ perm[ i ] ] ≤ x[ perm[ i + 1 ] ].
*
*
Note that this implementation does not allocate any object, contrarily to the implementation used to sort primitive types in {@link java.util.Arrays}, which switches to mergesort on large
* inputs.
*
* @param perm a permutation array indexing {@code x}.
* @param x the array to be sorted. */
public static void quickSortIndirect( final int perm[], final K[] x ) {
quickSortIndirect( perm, x, 0, x.length );
}
protected static class ForkJoinQuickSortIndirect extends RecursiveAction {
private static final long serialVersionUID = 1L;
private final int from;
private final int to;
private final int[] perm;
private final K[] x;
public ForkJoinQuickSortIndirect( final int perm[], final K[] x, final int from, final int to ) {
this.from = from;
this.to = to;
this.x = x;
this.perm = perm;
}
@Override
@SuppressWarnings("unchecked")
protected void compute() {
final K[] x = this.x;
final int len = to - from;
if ( len < PARALLEL_QUICKSORT_NO_FORK ) {
quickSortIndirect( perm, x, from, to );
return;
}
// Choose a partition element, v
int m = from + len / 2;
int l = from;
int n = to - 1;
int s = len / 8;
l = med3Indirect( perm, x, l, l + s, l + 2 * s );
m = med3Indirect( perm, x, m - s, m, m + s );
n = med3Indirect( perm, x, n - 2 * s, n - s, n );
m = med3Indirect( perm, x, l, m, n );
final K v = x[ perm[ m ] ];
// Establish Invariant: v* (v)* v*
int a = from, b = a, c = to - 1, d = c;
while ( true ) {
int comparison;
while ( b <= c && ( comparison = ( ( (Comparable)( x[ perm[ b ] ] ) ).compareTo( v ) ) ) <= 0 ) {
if ( comparison == 0 ) IntArrays.swap( perm, a++, b );
b++;
}
while ( c >= b && ( comparison = ( ( (Comparable)( x[ perm[ c ] ] ) ).compareTo( v ) ) ) >= 0 ) {
if ( comparison == 0 ) IntArrays.swap( perm, c, d-- );
c--;
}
if ( b > c ) break;
IntArrays.swap( perm, b++, c-- );
}
// Swap partition elements back to middle
int t;
s = Math.min( a - from, b - a );
IntArrays.swap( perm, from, b - s, s );
s = Math.min( d - c, to - d - 1 );
IntArrays.swap( perm, b, to - s, s );
// Recursively sort non-partition-elements
s = b - a;
t = d - c;
if ( s > 1 && t > 1 ) invokeAll( new ForkJoinQuickSortIndirect( perm, x, from, from + s ), new ForkJoinQuickSortIndirect( perm, x, to - t, to ) );
else if ( s > 1 ) invokeAll( new ForkJoinQuickSortIndirect( perm, x, from, from + s ) );
else invokeAll( new ForkJoinQuickSortIndirect( perm, x, to - t, to ) );
}
}
/** Sorts the specified range of elements according to the natural ascending order using a parallel indirect quicksort.
*
* The sorting algorithm is a tuned quicksort adapted from Jon L. Bentley and M. Douglas McIlroy, “Engineering a Sort Function”, Software: Practice and Experience, 23(11),
* pages 1249−1265, 1993.
*
*
This method implement an indirect sort. The elements of perm (which must be exactly the numbers in the interval [0..perm.length)) will be permuted so that
* x[ perm[ i ] ] ≤ x[ perm[ i + 1 ] ].
*
*
This implementation uses a {@link ForkJoinPool} executor service with {@link Runtime#availableProcessors()} parallel threads.
*
* @param perm a permutation array indexing {@code x}.
* @param x the array to be sorted.
* @param from the index of the first element (inclusive) to be sorted.
* @param to the index of the last element (exclusive) to be sorted. */
public static void parallelQuickSortIndirect( final int[] perm, final K[] x, final int from, final int to ) {
final ForkJoinPool pool = new ForkJoinPool( Runtime.getRuntime().availableProcessors() );
pool.invoke( new ForkJoinQuickSortIndirect( perm, x, from, to ) );
pool.shutdown();
}
/** Sorts an array according to the natural ascending order using a parallel indirect quicksort.
*
* The sorting algorithm is a tuned quicksort adapted from Jon L. Bentley and M. Douglas McIlroy, “Engineering a Sort Function”, Software: Practice and Experience, 23(11),
* pages 1249−1265, 1993.
*
*
This method implement an indirect sort. The elements of perm (which must be exactly the numbers in the interval [0..perm.length)) will be permuted so that
* x[ perm[ i ] ] ≤ x[ perm[ i + 1 ] ].
*
*
This implementation uses a {@link ForkJoinPool} executor service with {@link Runtime#availableProcessors()} parallel threads.
*
* @param perm a permutation array indexing {@code x}.
* @param x the array to be sorted. */
public static void parallelQuickSortIndirect( final int perm[], final K[] x ) {
parallelQuickSortIndirect( perm, x, 0, x.length );
}
/** Stabilizes a permutation.
*
* This method can be used to stabilize the permutation generated by an indirect sorting, assuming that initially the permutation array was in ascending order (e.g., the identity, as usually
* happens). This method scans the permutation, and for each non-singleton block of elements with the same associated values in {@code x}, permutes them in ascending order. The resulting
* permutation corresponds to a stable sort.
*
*
Usually combining an unstable indirect sort and this method is more efficient than using a stable sort, as most stable sort algorithms require a support array.
*
*
More precisely, assuming that x[ perm[ i ] ] ≤ x[ perm[ i + 1 ] ], after stabilization we will also have that x[ perm[ i ] ] = x[ perm[ i + 1 ] ] implies
* perm[ i ] ≤ perm[ i + 1 ].
*
* @param perm a permutation array indexing {@code x} so that it is sorted.
* @param x the sorted array to be stabilized.
* @param from the index of the first element (inclusive) to be stabilized.
* @param to the index of the last element (exclusive) to be stabilized. */
public static void stabilize( final int perm[], final K[] x, final int from, final int to ) {
int curr = from;
for ( int i = from + 1; i < to; i++ ) {
if ( x[ perm[ i ] ] != x[ perm[ curr ] ] ) {
if ( i - curr > 1 ) IntArrays.parallelQuickSort( perm, curr, i );
curr = i;
}
}
if ( to - curr > 1 ) IntArrays.parallelQuickSort( perm, curr, to );
}
/** Stabilizes a permutation.
*
* This method can be used to stabilize the permutation generated by an indirect sorting, assuming that initially the permutation array was in ascending order (e.g., the identity, as usually
* happens). This method scans the permutation, and for each non-singleton block of elements with the same associated values in {@code x}, permutes them in ascending order. The resulting
* permutation corresponds to a stable sort.
*
*
Usually combining an unstable indirect sort and this method is more efficient than using a stable sort, as most stable sort algorithms require a support array.
*
*
More precisely, assuming that x[ perm[ i ] ] ≤ x[ perm[ i + 1 ] ], after stabilization we will also have that x[ perm[ i ] ] = x[ perm[ i + 1 ] ] implies
* perm[ i ] ≤ perm[ i + 1 ].
*
* @param perm a permutation array indexing {@code x} so that it is sorted.
* @param x the sorted array to be stabilized. */
public static void stabilize( final int perm[], final K[] x ) {
stabilize( perm, x, 0, perm.length );
}
@SuppressWarnings("unchecked")
private static int med3( final K x[], final K[] y, final int a, final int b, final int c ) {
int t;
final int ab = ( t = ( ( (Comparable)( x[ a ] ) ).compareTo( x[ b ] ) ) ) == 0 ? ( ( (Comparable)( y[ a ] ) ).compareTo( y[ b ] ) ) : t;
final int ac = ( t = ( ( (Comparable)( x[ a ] ) ).compareTo( x[ c ] ) ) ) == 0 ? ( ( (Comparable)( y[ a ] ) ).compareTo( y[ c ] ) ) : t;
final int bc = ( t = ( ( (Comparable)( x[ b ] ) ).compareTo( x[ c ] ) ) ) == 0 ? ( ( (Comparable)( y[ b ] ) ).compareTo( y[ c ] ) ) : t;
return ( ab < 0 ?
( bc < 0 ? b : ac < 0 ? c : a ) :
( bc > 0 ? b : ac > 0 ? c : a ) );
}
private static void swap( final K x[], final K[] y, final int a, final int b ) {
final K t = x[ a ];
final K u = y[ a ];
x[ a ] = x[ b ];
y[ a ] = y[ b ];
x[ b ] = t;
y[ b ] = u;
}
private static void swap( final K[] x, final K[] y, int a, int b, final int n ) {
for ( int i = 0; i < n; i++, a++, b++ )
swap( x, y, a, b );
}
@SuppressWarnings("unchecked")
private static void selectionSort( final K[] a, final K[] b, final int from, final int to ) {
for ( int i = from; i < to - 1; i++ ) {
int m = i, u;
for ( int j = i + 1; j < to; j++ )
if ( ( u = ( ( (Comparable)( a[ j ] ) ).compareTo( a[ m ] ) ) ) < 0 || u == 0 && ( ( (Comparable)( b[ j ] ) ).compareTo( b[ m ] ) < 0 ) ) m = j;
if ( m != i ) {
K t = a[ i ];
a[ i ] = a[ m ];
a[ m ] = t;
t = b[ i ];
b[ i ] = b[ m ];
b[ m ] = t;
}
}
}
/** Sorts the specified range of elements of two arrays according to the natural lexicographical ascending order using quicksort.
*
* The sorting algorithm is a tuned quicksort adapted from Jon L. Bentley and M. Douglas McIlroy, “Engineering a Sort Function”, Software: Practice and Experience, 23(11),
* pages 1249−1265, 1993.
*
*
This method implements a lexicographical sorting of the arguments. Pairs of elements in the same position in the two provided arrays will be considered a single key, and permuted
* accordingly. In the end, either x[ i ] < x[ i + 1 ] or x[ i ] == x[ i + 1 ] and y[ i ] ≤ y[ i + 1 ].
*
* @param x the first array to be sorted.
* @param y the second array to be sorted.
* @param from the index of the first element (inclusive) to be sorted.
* @param to the index of the last element (exclusive) to be sorted. */
@SuppressWarnings("unchecked")
public static void quickSort( final K[] x, final K[] y, final int from, final int to ) {
final int len = to - from;
if ( len < QUICKSORT_NO_REC ) {
selectionSort( x, y, from, to );
return;
}
// Choose a partition element, v
int m = from + len / 2;
int l = from;
int n = to - 1;
if ( len > QUICKSORT_MEDIAN_OF_9 ) { // Big arrays, pseudomedian of 9
int s = len / 8;
l = med3( x, y, l, l + s, l + 2 * s );
m = med3( x, y, m - s, m, m + s );
n = med3( x, y, n - 2 * s, n - s, n );
}
m = med3( x, y, l, m, n ); // Mid-size, med of 3
final K v = x[ m ], w = y[ m ];
// Establish Invariant: v* (v)* v*
int a = from, b = a, c = to - 1, d = c;
while ( true ) {
int comparison, t;
while ( b <= c && ( comparison = ( t = ( ( (Comparable)( x[ b ] ) ).compareTo( v ) ) ) == 0 ? ( ( (Comparable)( y[ b ] ) ).compareTo( w ) ) : t ) <= 0 ) {
if ( comparison == 0 ) swap( x, y, a++, b );
b++;
}
while ( c >= b && ( comparison = ( t = ( ( (Comparable)( x[ c ] ) ).compareTo( v ) ) ) == 0 ? ( ( (Comparable)( y[ c ] ) ).compareTo( w ) ) : t ) >= 0 ) {
if ( comparison == 0 ) swap( x, y, c, d-- );
c--;
}
if ( b > c ) break;
swap( x, y, b++, c-- );
}
// Swap partition elements back to middle
int s;
s = Math.min( a - from, b - a );
swap( x, y, from, b - s, s );
s = Math.min( d - c, to - d - 1 );
swap( x, y, b, to - s, s );
// Recursively sort non-partition-elements
if ( ( s = b - a ) > 1 ) quickSort( x, y, from, from + s );
if ( ( s = d - c ) > 1 ) quickSort( x, y, to - s, to );
}
/** Sorts two arrays according to the natural lexicographical ascending order using quicksort.
*
* The sorting algorithm is a tuned quicksort adapted from Jon L. Bentley and M. Douglas McIlroy, “Engineering a Sort Function”, Software: Practice and Experience, 23(11),
* pages 1249−1265, 1993.
*
*
This method implements a lexicographical sorting of the arguments. Pairs of elements in the same position in the two provided arrays will be considered a single key, and permuted
* accordingly. In the end, either x[ i ] < x[ i + 1 ] or x[ i ] == x[ i + 1 ] and y[ i ] ≤ y[ i + 1 ].
*
* @param x the first array to be sorted.
* @param y the second array to be sorted. */
public static void quickSort( final K[] x, final K[] y ) {
ensureSameLength( x, y );
quickSort( x, y, 0, x.length );
}
protected static class ForkJoinQuickSort2 extends RecursiveAction {
private static final long serialVersionUID = 1L;
private final int from;
private final int to;
private final K[] x, y;
public ForkJoinQuickSort2( final K[] x, final K[] y, final int from, final int to ) {
this.from = from;
this.to = to;
this.x = x;
this.y = y;
}
@Override
@SuppressWarnings("unchecked")
protected void compute() {
final K[] x = this.x;
final K[] y = this.y;
final int len = to - from;
if ( len < PARALLEL_QUICKSORT_NO_FORK ) {
quickSort( x, y, from, to );
return;
}
// Choose a partition element, v
int m = from + len / 2;
int l = from;
int n = to - 1;
int s = len / 8;
l = med3( x, y, l, l + s, l + 2 * s );
m = med3( x, y, m - s, m, m + s );
n = med3( x, y, n - 2 * s, n - s, n );
m = med3( x, y, l, m, n );
final K v = x[ m ], w = y[ m ];
// Establish Invariant: v* (v)* v*
int a = from, b = a, c = to - 1, d = c;
while ( true ) {
int comparison, t;
while ( b <= c && ( comparison = ( t = ( ( (Comparable)( x[ b ] ) ).compareTo( v ) ) ) == 0 ? ( ( (Comparable)( y[ b ] ) ).compareTo( w ) ) : t ) <= 0 ) {
if ( comparison == 0 ) swap( x, y, a++, b );
b++;
}
while ( c >= b && ( comparison = ( t = ( ( (Comparable)( x[ c ] ) ).compareTo( v ) ) ) == 0 ? ( ( (Comparable)( y[ c ] ) ).compareTo( w ) ) : t ) >= 0 ) {
if ( comparison == 0 ) swap( x, y, c, d-- );
c--;
}
if ( b > c ) break;
swap( x, y, b++, c-- );
}
// Swap partition elements back to middle
int t;
s = Math.min( a - from, b - a );
swap( x, y, from, b - s, s );
s = Math.min( d - c, to - d - 1 );
swap( x, y, b, to - s, s );
s = b - a;
t = d - c;
// Recursively sort non-partition-elements
if ( s > 1 && t > 1 ) invokeAll( new ForkJoinQuickSort2( x, y, from, from + s ), new ForkJoinQuickSort2( x, y, to - t, to ) );
else if ( s > 1 ) invokeAll( new ForkJoinQuickSort2( x, y, from, from + s ) );
else invokeAll( new ForkJoinQuickSort2( x, y, to - t, to ) );
}
}
/** Sorts the specified range of elements of two arrays according to the natural lexicographical ascending order using a parallel quicksort.
*
* The sorting algorithm is a tuned quicksort adapted from Jon L. Bentley and M. Douglas McIlroy, “Engineering a Sort Function”, Software: Practice and Experience, 23(11),
* pages 1249−1265, 1993.
*
*
This method implements a lexicographical sorting of the arguments. Pairs of elements in the same position in the two provided arrays will be considered a single key, and permuted
* accordingly. In the end, either x[ i ] < x[ i + 1 ] or x[ i ] == x[ i + 1 ] and y[ i ] ≤ y[ i + 1 ].
*
*
This implementation uses a {@link ForkJoinPool} executor service with {@link Runtime#availableProcessors()} parallel threads.
*
* @param x the first array to be sorted.
* @param y the second array to be sorted.
* @param from the index of the first element (inclusive) to be sorted.
* @param to the index of the last element (exclusive) to be sorted. */
public static void parallelQuickSort( final K[] x, final K[] y, final int from, final int to ) {
final ForkJoinPool pool = new ForkJoinPool( Runtime.getRuntime().availableProcessors() );
pool.invoke( new ForkJoinQuickSort2( x, y, from, to ) );
pool.shutdown();
}
/** Sorts two arrays according to the natural lexicographical ascending order using a parallel quicksort.
*
* The sorting algorithm is a tuned quicksort adapted from Jon L. Bentley and M. Douglas McIlroy, “Engineering a Sort Function”, Software: Practice and Experience, 23(11),
* pages 1249−1265, 1993.
*
*
This method implements a lexicographical sorting of the arguments. Pairs of elements in the same position in the two provided arrays will be considered a single key, and permuted
* accordingly. In the end, either x[ i ] < x[ i + 1 ] or x[ i ] == x[ i + 1 ] and y[ i ] ≤ y[ i + 1 ].
*
*
This implementation uses a {@link ForkJoinPool} executor service with {@link Runtime#availableProcessors()} parallel threads.
*
* @param x the first array to be sorted.
* @param y the second array to be sorted. */
public static void parallelQuickSort( final K[] x, final K[] y ) {
ensureSameLength( x, y );
parallelQuickSort( x, y, 0, x.length );
}
/** Sorts the specified range of elements according to the natural ascending order using mergesort, using a given pre-filled support array.
*
* This sort is guaranteed to be stable: equal elements will not be reordered as a result of the sort. Moreover, no support arrays will be allocated.
*
* @param a the array to be sorted.
* @param from the index of the first element (inclusive) to be sorted.
* @param to the index of the last element (exclusive) to be sorted.
* @param supp a support array containing at least to elements, and whose entries are identical to those of {@code a} in the specified range. */
@SuppressWarnings("unchecked")
public static void mergeSort( final K a[], final int from, final int to, final K supp[] ) {
int len = to - from;
// Insertion sort on smallest arrays
if ( len < MERGESORT_NO_REC ) {
insertionSort( a, from, to );
return;
}
// Recursively sort halves of a into supp
final int mid = ( from + to ) >>> 1;
mergeSort( supp, from, mid, a );
mergeSort( supp, mid, to, a );
// If list is already sorted, just copy from supp to a. This is an
// optimization that results in faster sorts for nearly ordered lists.
if ( ( ( (Comparable)( supp[ mid - 1 ] ) ).compareTo( supp[ mid ] ) <= 0 ) ) {
System.arraycopy( supp, from, a, from, len );
return;
}
// Merge sorted halves (now in supp) into a
for ( int i = from, p = from, q = mid; i < to; i++ ) {
if ( q >= to || p < mid && ( ( (Comparable)( supp[ p ] ) ).compareTo( supp[ q ] ) <= 0 ) ) a[ i ] = supp[ p++ ];
else a[ i ] = supp[ q++ ];
}
}
/** Sorts the specified range of elements according to the natural ascending order using mergesort.
*
* This sort is guaranteed to be stable: equal elements will not be reordered as a result of the sort. An array as large as a will be allocated by this method.
*
* @param a the array to be sorted.
* @param from the index of the first element (inclusive) to be sorted.
* @param to the index of the last element (exclusive) to be sorted. */
public static void mergeSort( final K a[], final int from, final int to ) {
mergeSort( a, from, to, a.clone() );
}
/** Sorts an array according to the natural ascending order using mergesort.
*
* This sort is guaranteed to be stable: equal elements will not be reordered as a result of the sort. An array as large as a will be allocated by this method.
*
* @param a the array to be sorted. */
public static void mergeSort( final K a[] ) {
mergeSort( a, 0, a.length );
}
/** Sorts the specified range of elements according to the order induced by the specified comparator using mergesort, using a given pre-filled support array.
*
* This sort is guaranteed to be stable: equal elements will not be reordered as a result of the sort. Moreover, no support arrays will be allocated.
*
* @param a the array to be sorted.
* @param from the index of the first element (inclusive) to be sorted.
* @param to the index of the last element (exclusive) to be sorted.
* @param comp the comparator to determine the sorting order.
* @param supp a support array containing at least to elements, and whose entries are identical to those of {@code a} in the specified range. */
public static void mergeSort( final K a[], final int from, final int to, Comparator comp, final K supp[] ) {
int len = to - from;
// Insertion sort on smallest arrays
if ( len < MERGESORT_NO_REC ) {
insertionSort( a, from, to, comp );
return;
}
// Recursively sort halves of a into supp
final int mid = ( from + to ) >>> 1;
mergeSort( supp, from, mid, comp, a );
mergeSort( supp, mid, to, comp, a );
// If list is already sorted, just copy from supp to a. This is an
// optimization that results in faster sorts for nearly ordered lists.
if ( comp.compare( supp[ mid - 1 ], supp[ mid ] ) <= 0 ) {
System.arraycopy( supp, from, a, from, len );
return;
}
// Merge sorted halves (now in supp) into a
for ( int i = from, p = from, q = mid; i < to; i++ ) {
if ( q >= to || p < mid && comp.compare( supp[ p ], supp[ q ] ) <= 0 ) a[ i ] = supp[ p++ ];
else a[ i ] = supp[ q++ ];
}
}
/** Sorts the specified range of elements according to the order induced by the specified comparator using mergesort.
*
* This sort is guaranteed to be stable: equal elements will not be reordered as a result of the sort. An array as large as a will be allocated by this method.
*
* @param a the array to be sorted.
* @param from the index of the first element (inclusive) to be sorted.
* @param to the index of the last element (exclusive) to be sorted.
* @param comp the comparator to determine the sorting order. */
public static void mergeSort( final K a[], final int from, final int to, Comparator comp ) {
mergeSort( a, from, to, comp, a.clone() );
}
/** Sorts an array according to the order induced by the specified comparator using mergesort.
*
* This sort is guaranteed to be stable: equal elements will not be reordered as a result of the sort. An array as large as a will be allocated by this method.
*
* @param a the array to be sorted.
* @param comp the comparator to determine the sorting order. */
public static void mergeSort( final K a[], Comparator comp ) {
mergeSort( a, 0, a.length, comp );
}
/** Searches a range of the specified array for the specified value using the binary search algorithm. The range must be sorted prior to making this call. If it is not sorted, the results are
* undefined. If the range contains multiple elements with the specified value, there is no guarantee which one will be found.
*
* @param a the array to be searched.
* @param from the index of the first element (inclusive) to be searched.
* @param to the index of the last element (exclusive) to be searched.
* @param key the value to be searched for.
* @return index of the search key, if it is contained in the array; otherwise, (-(insertion point) - 1). The insertion point is defined as the the point at which the
* value would be inserted into the array: the index of the first element greater than the key, or the length of the array, if all elements in the array are less than the specified key. Note that
* this guarantees that the return value will be ≥ 0 if and only if the key is found.
* @see java.util.Arrays */
@SuppressWarnings("unchecked")
public static int binarySearch( final K[] a, int from, int to, final K key ) {
K midVal;
to--;
while ( from <= to ) {
final int mid = ( from + to ) >>> 1;
midVal = a[ mid ];
final int cmp = ( (Comparable)midVal ).compareTo( key );
if ( cmp < 0 ) from = mid + 1;
else if ( cmp > 0 ) to = mid - 1;
else return mid;
}
return -( from + 1 );
}
/** Searches an array for the specified value using the binary search algorithm. The range must be sorted prior to making this call. If it is not sorted, the results are undefined. If the range
* contains multiple elements with the specified value, there is no guarantee which one will be found.
*
* @param a the array to be searched.
* @param key the value to be searched for.
* @return index of the search key, if it is contained in the array; otherwise, (-(insertion point) - 1). The insertion point is defined as the the point at which the
* value would be inserted into the array: the index of the first element greater than the key, or the length of the array, if all elements in the array are less than the specified key. Note that
* this guarantees that the return value will be ≥ 0 if and only if the key is found.
* @see java.util.Arrays */
public static int binarySearch( final K[] a, final K key ) {
return binarySearch( a, 0, a.length, key );
}
/** Searches a range of the specified array for the specified value using the binary search algorithm and a specified comparator. The range must be sorted following the comparator prior to making
* this call. If it is not sorted, the results are undefined. If the range contains multiple elements with the specified value, there is no guarantee which one will be found.
*
* @param a the array to be searched.
* @param from the index of the first element (inclusive) to be searched.
* @param to the index of the last element (exclusive) to be searched.
* @param key the value to be searched for.
* @param c a comparator.
* @return index of the search key, if it is contained in the array; otherwise, (-(insertion point) - 1). The insertion point is defined as the the point at which the
* value would be inserted into the array: the index of the first element greater than the key, or the length of the array, if all elements in the array are less than the specified key. Note that
* this guarantees that the return value will be ≥ 0 if and only if the key is found.
* @see java.util.Arrays */
public static int binarySearch( final K[] a, int from, int to, final K key, final Comparator c ) {
K midVal;
to--;
while ( from <= to ) {
final int mid = ( from + to ) >>> 1;
midVal = a[ mid ];
final int cmp = c.compare( midVal, key );
if ( cmp < 0 ) from = mid + 1;
else if ( cmp > 0 ) to = mid - 1;
else return mid; // key found
}
return -( from + 1 );
}
/** Searches an array for the specified value using the binary search algorithm and a specified comparator. The range must be sorted following the comparator prior to making this call. If it is not
* sorted, the results are undefined. If the range contains multiple elements with the specified value, there is no guarantee which one will be found.
*
* @param a the array to be searched.
* @param key the value to be searched for.
* @param c a comparator.
* @return index of the search key, if it is contained in the array; otherwise, (-(insertion point) - 1). The insertion point is defined as the the point at which the
* value would be inserted into the array: the index of the first element greater than the key, or the length of the array, if all elements in the array are less than the specified key. Note that
* this guarantees that the return value will be ≥ 0 if and only if the key is found.
* @see java.util.Arrays */
public static int binarySearch( final K[] a, final K key, final Comparator c ) {
return binarySearch( a, 0, a.length, key, c );
}
/** Shuffles the specified array fragment using the specified pseudorandom number generator.
*
* @param a the array to be shuffled.
* @param from the index of the first element (inclusive) to be shuffled.
* @param to the index of the last element (exclusive) to be shuffled.
* @param random a pseudorandom number generator (please use a XorShift* generator).
* @return a. */
public static K[] shuffle( final K[] a, final int from, final int to, final Random random ) {
for ( int i = to - from; i-- != 0; ) {
final int p = random.nextInt( i + 1 );
final K t = a[ from + i ];
a[ from + i ] = a[ from + p ];
a[ from + p ] = t;
}
return a;
}
/** Shuffles the specified array using the specified pseudorandom number generator.
*
* @param a the array to be shuffled.
* @param random a pseudorandom number generator (please use a XorShift* generator).
* @return a. */
public static K[] shuffle( final K[] a, final Random random ) {
for ( int i = a.length; i-- != 0; ) {
final int p = random.nextInt( i + 1 );
final K t = a[ i ];
a[ i ] = a[ p ];
a[ p ] = t;
}
return a;
}
/** Reverses the order of the elements in the specified array.
*
* @param a the array to be reversed.
* @return a. */
public static K[] reverse( final K[] a ) {
final int length = a.length;
for ( int i = length / 2; i-- != 0; ) {
final K t = a[ length - i - 1 ];
a[ length - i - 1 ] = a[ i ];
a[ i ] = t;
}
return a;
}
/** Reverses the order of the elements in the specified array fragment.
*
* @param a the array to be reversed.
* @param from the index of the first element (inclusive) to be reversed.
* @param to the index of the last element (exclusive) to be reversed.
* @return a. */
public static K[] reverse( final K[] a, final int from, final int to ) {
final int length = to - from;
for ( int i = length / 2; i-- != 0; ) {
final K t = a[ from + length - i - 1 ];
a[ from + length - i - 1 ] = a[ from + i ];
a[ from + i ] = t;
}
return a;
}
/** A type-specific content-based hash strategy for arrays. */
private static final class ArrayHashStrategy implements Hash.Strategy, java.io.Serializable {
private static final long serialVersionUID = -7046029254386353129L;
public int hashCode( final K[] o ) {
return java.util.Arrays.hashCode( o );
}
public boolean equals( final K[] a, final K[] b ) {
return java.util.Arrays.equals( a, b );
}
}
/** A type-specific content-based hash strategy for arrays.
*
* This hash strategy may be used in custom hash collections whenever keys are arrays, and they must be considered equal by content. This strategy will handle null correctly, and
* it is serializable. */
@SuppressWarnings({ "rawtypes" })
public final static Hash.Strategy HASH_STRATEGY = new ArrayHashStrategy();
}