src.it.unimi.dsi.fastutil.ints.IntHeapSemiIndirectPriorityQueue Maven / Gradle / Ivy
/* 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) */
/* Primitive-type-only definitions (keys) */
/* Object/Reference-only definitions (values) */
/*
* Copyright (C) 2003-2013 Paolo Boldi and 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.
*/
package it.unimi.dsi.fastutil.ints;
import java.util.NoSuchElementException;
import it.unimi.dsi.fastutil.ints.IntArrays;
import it.unimi.dsi.fastutil.AbstractIndirectPriorityQueue;
/** A type-specific heap-based semi-indirect priority queue.
*
* Instances of this class use as reference list a reference array,
* which must be provided to each constructor. The priority queue is
* represented using a heap. The heap is enlarged as needed, but it is never
* shrunk. Use the {@link #trim()} method to reduce its size, if necessary.
*
*
This implementation allows one to enqueue several time the same index, but
* you must be careful when calling {@link #changed()}.
*/
public class IntHeapSemiIndirectPriorityQueue extends AbstractIndirectPriorityQueue implements IntIndirectPriorityQueue {
/** The reference array. */
protected int refArray[];
/** The semi-indirect heap. */
protected int heap[] = IntArrays.EMPTY_ARRAY;
/** The number of elements in this queue. */
protected int size;
/** The type-specific comparator used in this queue. */
protected IntComparator c;
/** Creates a new empty queue without elements with a given capacity and comparator.
*
* @param refArray the reference array.
* @param capacity the initial capacity of this queue.
* @param c the comparator used in this queue, or null for the natural order.
*/
public IntHeapSemiIndirectPriorityQueue( int[] refArray, int capacity, IntComparator c ) {
if ( capacity > 0 ) this.heap = new int[ capacity ];
this.refArray = refArray;
this.c = c;
}
/** Creates a new empty queue with given capacity and using the natural order.
*
* @param refArray the reference array.
* @param capacity the initial capacity of this queue.
*/
public IntHeapSemiIndirectPriorityQueue( int[] refArray, int capacity ) {
this( refArray, capacity, null );
}
/** Creates a new empty queue with capacity equal to the length of the reference array and a given comparator.
*
* @param refArray the reference array.
* @param c the comparator used in this queue, or null for the natural order.
*/
public IntHeapSemiIndirectPriorityQueue( int[] refArray, IntComparator c ) {
this( refArray, refArray.length, c );
}
/** Creates a new empty queue with capacity equal to the length of the reference array and using the natural order.
* @param refArray the reference array.
*/
public IntHeapSemiIndirectPriorityQueue( final int[] refArray ) {
this( refArray, refArray.length, null );
}
/** Wraps a given array in a queue using a given comparator.
*
* The queue returned by this method will be backed by the given array.
* The first size element of the array will be rearranged so to form a heap (this is
* more efficient than enqueing the elements of a one by one).
*
* @param refArray the reference array.
* @param a an array of indices into refArray.
* @param size the number of elements to be included in the queue.
* @param c the comparator used in this queue, or null for the natural order.
*/
public IntHeapSemiIndirectPriorityQueue( final int[] refArray, final int[] a, int size, final IntComparator c ) {
this( refArray, 0, c );
this.heap = a;
this.size = size;
IntSemiIndirectHeaps.makeHeap( refArray, a, size, c );
}
/** Wraps a given array in a queue using a given comparator.
*
*
The queue returned by this method will be backed by the given array.
* The elements of the array will be rearranged so to form a heap (this is
* more efficient than enqueing the elements of a one by one).
*
* @param refArray the reference array.
* @param a an array of indices into refArray.
* @param c the comparator used in this queue, or null for the natural order.
*/
public IntHeapSemiIndirectPriorityQueue( final int[] refArray, final int[] a, final IntComparator c ) {
this( refArray, a, a.length, c );
}
/** Wraps a given array in a queue using the natural order.
*
*
The queue returned by this method will be backed by the given array.
* The first size element of the array will be rearranged so to form a heap (this is
* more efficient than enqueing the elements of a one by one).
*
* @param refArray the reference array.
* @param a an array of indices into refArray.
* @param size the number of elements to be included in the queue.
*/
public IntHeapSemiIndirectPriorityQueue( final int[] refArray, final int[] a, int size ) {
this( refArray, a, size, null );
}
/** Wraps a given array in a queue using the natural order.
*
*
The queue returned by this method will be backed by the given array.
* The elements of the array will be rearranged so to form a heap (this is
* more efficient than enqueing the elements of a one by one).
*
* @param refArray the reference array.
* @param a an array of indices into refArray.
*/
public IntHeapSemiIndirectPriorityQueue( final int[] refArray, final int[] a ) {
this( refArray, a, a.length );
}
/** Ensures that the given index is a valid reference.
*
* @param index an index in the reference array.
* @throws IndexOutOfBoundsException if the given index is negative or larger than the reference array length.
*/
protected void ensureElement( final int index ) {
if ( index < 0 ) throw new IndexOutOfBoundsException( "Index (" + index + ") is negative" );
if ( index >= refArray.length ) throw new IndexOutOfBoundsException( "Index (" + index + ") is larger than or equal to reference array size (" + refArray.length + ")" );
}
public void enqueue( int x ) {
ensureElement( x );
if ( size == heap.length ) heap = IntArrays.grow( heap, size + 1 );
heap[ size++ ] = x;
IntSemiIndirectHeaps.upHeap( refArray, heap, size, size - 1, c );
}
public int dequeue() {
if ( size == 0 ) throw new NoSuchElementException();
final int result = heap[ 0 ];
heap[ 0 ] = heap[ --size ];
if ( size != 0 ) IntSemiIndirectHeaps.downHeap( refArray, heap, size, 0, c );
return result;
}
public int first() {
if ( size == 0 ) throw new NoSuchElementException();
return heap[ 0 ];
}
/** {@inheritDoc}
*
*
The caller must guarantee that when this method is called the
* index of the first element appears just once in the queue. Failure to do so
* will bring the queue in an inconsistent state, and will cause
* unpredictable behaviour.
*/
public void changed() {
IntSemiIndirectHeaps.downHeap( refArray, heap, size, 0, c );
}
/** Rebuilds this heap in a bottom-up fashion.
*/
public void allChanged() {
IntSemiIndirectHeaps.makeHeap( refArray, heap, size, c );
}
public int size() { return size; }
public void clear() { size = 0; }
/** Trims the backing array so that it has exactly {@link #size()} elements.
*/
public void trim() {
heap = IntArrays.trim( heap, size );
}
public IntComparator comparator() { return c; }
public int front( final int[] a ) {
return c == null ? IntSemiIndirectHeaps.front( refArray, heap, size, a ) : IntSemiIndirectHeaps.front( refArray, heap, size, a, c );
}
public String toString() {
StringBuffer s = new StringBuffer();
s.append( "[" );
for ( int i = 0; i < size; i++ ) {
if ( i != 0 ) s.append( ", " );
s.append( refArray[ heap [ i ] ] );
}
s.append( "]" );
return s.toString();
}
}