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98 lines (84 loc) · 1.96 KB
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package sort;
public class QuickSort {
/**
* 快速排序
*
* @param arr
* @param left
* @param right
* @return
*/
public static int[] quickSort(int[] arr, int left, int right) {
if (left >= right) {
return arr;
}
int pivot = partition1(arr, left, right);
quickSort(arr, left, pivot - 1);
quickSort(arr, pivot + 1, right);
return arr;
}
/**
* find pivot （从右边开始遍历）
*
* @param arr
* @param left
* @param right
* @return
*/
public static int partition1(int[] arr, int left, int right) {
int pivot = arr[left];
int i = left + 1;
int j = right;
while (i <= j) {
//从右边开始
while (i <= j && arr[j] >= pivot) {
j--;
}
//再遍历左边
while (i <= j && arr[i] <= pivot) {
i++;
}
if (i >= j) {
break;
}
int temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
arr[left] = arr[j];
arr[j] = pivot;
return j;
}
/**
* find pivot （从左边开始遍历）
*
* @param arr
* @param left
* @param right
* @return
*/
public static int partition2(int[] arr, int left, int right) {
int pivot = arr[left];
int i = left + 1;
int j = right;
while (i <= j) {
//从左边开始
while (i <= j && arr[i] <= pivot) {
i++;
}
//再遍历右边
while (i <= j && arr[j] >= pivot) {
j--;
}
if (i >= j) {
break;
}
int temp = arr[i];
arr[i] = arr[j];
arr[j] = temp;
}
arr[left] = arr[j];
arr[j] = pivot;
return j;
}
}