import java.util.Arrays;
/**
* 随机快速排序
* @author Administrator
*
*/
public class Code04_QuickSort {
public static void quickSort(int[] arr){
if(arr == null || arr.length < 2)
return ;
quickSort(arr, 0, arr.length - 1);
}
public static void quickSort(int[] arr, int left, int right){
if(left < right){
swap(arr, left + (int)(Math.random() * (right - left + 1)), right);
int[] p = partition(arr, left, right);
quickSort(arr, left, p[0] - 1);
quickSort(arr, p[1] + 1, right);
}
}
// 归并排序
public static int[] partition(int[] arr, int left, int right){
int less = left - 1;
int more = right;
while(left < more){
if(arr[left] < arr[right]){
swap(arr, ++less, left++);
} else if(arr[left] > arr[right]){
swap(arr, --more, left);
} else {
left++;
}
}
swap(arr, more, right);
return new int[] {less + 1, more - 1};
}
public static void swap(int[] arr, int a, int b){
int temp;
temp = arr[a];
arr[a] = arr[b];
arr[b] = 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();
}
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);
quickSort(arr1);
comparator(arr2);
if (!isEqual(arr1, arr2)) {
succeed = false;
printArray(arr1);
printArray(arr2);
break;
}
}
System.out.println(succeed ? "Nice!" : "Fucking fucked!");
int[] arr = generateRandomArray(maxSize, maxValue);
printArray(arr);
quickSort(arr);
printArray(arr);
}
}
测试结果:
Nice!
20 42 -61 -67 -61
-67 -61 -61 20 42