堆排Java代码实现

  1 package com.cmbc.test1;
  2 
  3 import java.util.Arrays;
  4 
  5 public class HeapSortion {
  6     
  7     
  8     public static void heapSort(int[] arr){
  9         if(arr==null||arr.length<2){
 10             return;
 11         }
 12         //建立大根堆
 13         for(int i = 0;i<arr.length;i++){
 14             heapInsert(arr,i);
 15         }
 16         //建立完大根堆之后，二叉树的size和数组长度是一致的；
 17         int size = arr.length;
 18         swap(arr,0,--size);
 19         while(size>0){
 20             heapify(arr,0,size);
 21             swap(arr,0,--size);
 22         }
 23     }
 24     
 25     public static void heapInsert(int[] arr,int index){
 26         while(arr[index]>arr[(index-1)/2]){
 27             swap(arr,index,(index-1)/2);
 28             index = (index-1)/2;
 29         }
 30     }
 31     
 32     public static void swap(int[] arr, int i, int j) {
 33         int tmp = arr[i];
 34         arr[i] = arr[j];
 35         arr[j] = tmp;
 36     }
 37     
 38     
 39     public static void printArray(int[] arr) {
 40         if (arr == null) {
 41             return;
 42         }
 43         for (int i = 0; i < arr.length; i++) {
 44             System.out.print(arr[i] + " ");
 45         }
 46         System.out.println();
 47     }
 48     
 49     public static void  heapify(int[] arr,int index,int size){
 50         int left = 2*index+1;
 51         while(left<size){
 52             int largest = left+1<size&&arr[left+1]>arr[left]?left+1:left;
 53             largest = arr[largest]>arr[index]?largest:index;
 54             if(largest==index){
 55                 break;
 56             }
 57             swap(arr,largest,index);
 58             index = largest;
 59             left = largest*2+1;
 60         }
 61     }
 62     
 63     public static boolean isEqual(int[] arr1, int[] arr2) {
 64         if ((arr1 == null && arr2 != null) || (arr1 != null && arr2 == null)) {
 65             return false;
 66         }
 67         if (arr1 == null && arr2 == null) {
 68             return true;
 69         }
 70         if (arr1.length != arr2.length) {
 71             return false;
 72         }
 73         for (int i = 0; i < arr1.length; i++) {
 74             if (arr1[i] != arr2[i]) {
 75                 return false;
 76             }
 77         }
 78         return true;
 79     }
 80     
 81     public static int[] generateRandomArray(int maxSize, int maxValue) {
 82         int[] arr = new int[(int) ((maxSize + 1) * Math.random())];
 83         for (int i = 0; i < arr.length; i++) {
 84             arr[i] = (int) ((maxValue + 1) * Math.random()) - (int) (maxValue * Math.random());
 85         }
 86         return arr;
 87     }
 88     
 89     public static int[] copyArray(int[] arr) {
 90         if (arr == null) {
 91             return null;
 92         }
 93         int[] res = new int[arr.length];
 94         for (int i = 0; i < arr.length; i++) {
 95             res[i] = arr[i];
 96         }
 97         return res;
 98     }
 99     
100     public static void main(String[] args) {
101         int testTime = 500000;
102         int maxSize = 100;
103         int maxValue = 100;
104         boolean succeed = true;
105         for (int i = 0; i < testTime; i++) {
106             int[] arr1 = generateRandomArray(maxSize, maxValue);
107             int[] arr2 = copyArray(arr1);
108             heapSort(arr1);
109             Arrays.sort(arr2);
110             if (!isEqual(arr1, arr2)) {
111                 succeed = false;
112                 break;
113             }
114         }
115         System.out.println(succeed ? "正确!" : "请仔细检查");
116 
117         int[] arr = generateRandomArray(maxSize, maxValue);
118         printArray(arr);
119         heapSort(arr);
120         printArray(arr);
121     }
122 
123 }