import java.util.Arrays;
/**
* 堆排序
* @author Administrator
*
*/
public class Code05_heapSort {
// 大根树
public static void heapSort(int[] arr){
if(arr == null || arr.length < 2)
return ;
for(int i = 0; i < arr.length; i++){
heapInsert(arr, i);
}
int size = arr.length;
swap(arr, 0, --size);
while(size > 0){
heapify(arr, 0, size);
swap(arr, 0, --size);
}
}
public static void heapify(int[] arr, int index, int size){
int left = 2 * index + 1;
while(left < size){
int largest = left + 1 < size && arr[left + 1] > arr[left] ? left + 1 : left;
largest = arr[largest] > arr[index] ? largest : index;
if(largest == index)
break;
swap(arr, largest, index);
index = largest;
left = 2 * index + 1;
}
}
public static void heapInsert(int[] arr, int index){
while(arr[index] > arr[(index-1) / 2]){
swap(arr, index, (index-1) / 2);
index = (index-1) / 2;
}
}
public static void swap(int[] arr, int i, int j){
int temp;
temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
// for test
public static void comparator(int[] arr) {
Arrays.sort(arr);
}
// for test
public static int[] generateRandomArray(int maxSize, int maxValue) {
int[] arr = new int[(int) ((maxSize + 1) * Math.random())];
for (int i = 0; i < arr.length; i++) {
arr[i] = (int) ((maxValue + 1) * Math.random()) - (int) (maxValue * Math.random());
}
return arr;
}
// for test
public static int[] copyArray(int[] arr) {
if (arr == null) {
return null;
}
int[] res = new int[arr.length];
for (int i = 0; i < arr.length; i++) {
res[i] = arr[i];
}
return res;
}
// for test
public static boolean isEqual(int[] arr1, int[] arr2) {
if ((arr1 == null && arr2 != null) || (arr1 != null && arr2 == null)) {
return false;
}
if (arr1 == null && arr2 == null) {
return true;
}
if (arr1.length != arr2.length) {
return false;
}
for (int i = 0; i < arr1.length; i++) {
if (arr1[i] != arr2[i]) {
return false;
}
}
return true;
}
// for test
public static void printArray(int[] arr) {
if (arr == null) {
return;
}
for (int i = 0; i < arr.length; i++) {
System.out.print(arr[i] + " ");
}
System.out.println();
}
// for test
public static void main(String[] args) {
int testTime = 500000;
int maxSize = 100;
int maxValue = 100;
boolean succeed = true;
for (int i = 0; i < testTime; i++) {
int[] arr1 = generateRandomArray(maxSize, maxValue);
int[] arr2 = copyArray(arr1);
heapSort(arr1);
comparator(arr2);
if (!isEqual(arr1, arr2)) {
succeed = false;
break;
}
}
System.out.println(succeed ? "Nice!" : "Fucking fucked!");
int[] arr = generateRandomArray(maxSize, maxValue);
printArray(arr);
heapSort(arr);
printArray(arr);
}
}
算法入门-堆排序
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转载自blog.csdn.net/scanf_print_/article/details/82812145
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