数据结构之堆排序

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package com.zhiru;/* * 堆排序 * 时间复杂度：O(n*log2n) * 空间复杂度：O(1) * 不稳定的排序算法 */public class HeapSort {private int[] heap;private int maxSize;// 堆的最大容量private int currentSize;// 堆目前容量private static int defaultSize = 10;HeapSort(int sz) {maxSize = (defaultSize < sz ? sz : defaultSize);heap = new int[maxSize];currentSize = 0;//}HeapSort(int[] a) {int len = a.length;maxSize = (defaultSize < len ? len : defaultSize);heap = new int[maxSize];for (int i = 0; i < len; i++)heap[i] = a[i];currentSize = len;int currentPos = (currentSize - 2) / 2;// 自下向上调整为最大堆while (currentPos >= 0) {siftDown(currentPos, currentSize - 1);currentPos--;}}// 最大堆的局部调整算法.private void siftDown(int start, int m) {int i, j;i = start;// 开始节点j = 2 * i + 1;// 开始节点的左子树int temp = heap[i];while (j <= m) {if (j < m && heap[j] < heap[j + 1])j++;// 左右子树那个大，走那边if (temp >= heap[j])break;// 父节点较子女结点大，跳出循环。else {heap[i] = heap[j];i = j;j = 2 * i + 1;}}heap[i] = temp;// 回放}public void sort() {// for(int i=(currentSize-2)/2;i>=0;i--)// siftDown(i,currentSize-1);// heap[0]有最大的排序码，每次循环将最大heap[0]与 heap[n-2]交换// 然后将剩余元素调整为最大堆，堆顶就是次最大排序码，直到排好序为止。for (int j = currentSize - 1; j >= 0; j--) {printHeap();System.out.print("\n");heap[0] ^= heap[j];heap[j] = heap[0] ^ heap[j];heap[0] ^= heap[j];siftDown(0, j - 1);}}public void printHeap() {if (heap != null && currentSize > 0) {for (int i = 0; i < currentSize; i++) {System.out.print(heap[i] + " ");}}}}

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