从给定节点开始的heapify堆校验检查节点的每个子节点，如果它大于父节点，它将交换两个节点并堆放该子节点

/* 来 自 n o w j a v a . c o m*/


//package com.nowjava;


public class Main {

    /**

     * heapifies starting from a given node

     * 

     * heapifying checks each child of the node and if it is greater than the

     * parent it swaps the two and heapifies the child

     * 

     * @param heap

     *            the heap to heapify in

     * @param index

     *            the index of the node to heapify

     * @param heapSize

     *            the size of the heap

     */

    public static void heapify(Comparable[] heap, int index, int heapSize) {

        int leftIndex = 2 * index;

        int rightIndex = 2 * index + 1;

        if (leftIndex <= heapSize) {

            if (heap[leftIndex].compareTo(heap[index]) > 0) {

                swap(heap, index, leftIndex);

                heapify(heap, leftIndex, heapSize);

            }

        }

        if (rightIndex <= heapSize) {

            if (heap[rightIndex].compareTo(heap[index]) > 0) {

                swap(heap, index, rightIndex);
                /**
                时代Java - nowjava.com 提供 
                **/

                heapify(heap, rightIndex, heapSize);

            }

        }

    }