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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) */
/* Primitive-type-only definitions (keys) */
/* Object/Reference-only definitions (values) */
/*
* Copyright (C) 2003-2016 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.shorts;
/**
* A class providing static methods and objects that do useful things with
* heaps.
*
*
* The static methods of this class allow to treat arrays as 0-based heaps. They
* are used in the implementation of heap-based queues, but they may be also
* used directly.
*
*/
public class ShortHeaps {
private ShortHeaps() {
}
/**
* Moves the given element down into the heap until it reaches the lowest
* possible position.
*
* @param heap
* the heap (starting at 0).
* @param size
* the number of elements in the heap.
* @param i
* the index of the element that must be moved down.
* @param c
* a type-specific comparator, or null for the
* natural order.
* @return the new position of the element of index i.
*/
public static int downHeap(final short[] heap, final int size, int i,
final ShortComparator c) {
assert i < size;
final short e = heap[i];
int child;
if (c == null)
while ((child = (i << 1) + 1) < size) {
short t = heap[child];
final int right = child + 1;
if (right < size && ((heap[right]) < (t)))
t = heap[child = right];
if (((e) <= (t)))
break;
heap[i] = t;
i = child;
}
else
while ((child = (i << 1) + 1) < size) {
short t = heap[child];
final int right = child + 1;
if (right < size && c.compare(heap[right], t) < 0)
t = heap[child = right];
if (c.compare(e, t) <= 0)
break;
heap[i] = t;
i = child;
}
heap[i] = e;
return i;
}
/**
* Moves the given element up in the heap until it reaches the highest
* possible position.
*
* @param heap
* the heap (starting at 0).
* @param size
* the number of elements in the heap.
* @param i
* the index of the element that must be moved up.
* @param c
* a type-specific comparator, or null for the
* natural order.
* @return the new position of the element of index i.
*/
public static int upHeap(final short[] heap, final int size, int i,
final ShortComparator c) {
assert i < size;
final short e = heap[i];
if (c == null)
while (i != 0) {
final int parent = (i - 1) >>> 1;
final short t = heap[parent];
if (((t) <= (e)))
break;
heap[i] = t;
i = parent;
}
else
while (i != 0) {
final int parent = (i - 1) >>> 1;
final short t = heap[parent];
if (c.compare(t, e) <= 0)
break;
heap[i] = t;
i = parent;
}
heap[i] = e;
return i;
}
/**
* Makes an array into a heap.
*
* @param heap
* the heap (starting at 0).
* @param size
* the number of elements in the heap.
* @param c
* a type-specific comparator, or null for the
* natural order.
*/
public static void makeHeap(final short[] heap, final int size,
final ShortComparator c) {
int i = size >>> 1;
while (i-- != 0)
downHeap(heap, size, i, c);
}
}