标准模版
交换法
单函数法
public static void quickSort(int[] arr, int start, int end) {if (start >= end) {return;}int idx = start;int pivot = arr[idx];int left = start, right = end;while (left < right) {while (left < right && arr[right] >= pivot) {right--;}while(left < right && arr[left] <= pivot) {left++;}swap(arr, left, right);}// 从此行开始，left == rightswap(arr, idx, left);if (start < left) {quickSort(arr, start, left - 1);}if (right < end) {quickSort(arr, right + 1, end);}
}
双函数法
/*** 快速排序* <p>* 这一层的逻辑基本不会变，注意递归退出条件** @param nums* @param start* @param end*/
public static void quickSort(int[] nums, int start, int end) {if (start < end) {int index = partition(nums, start, end);quickSort(nums, start, index - 1);quickSort(nums, index + 1, end);}
}/*** 交换法，即Hoare法** @param arr* @param start* @param end* @return*/
public static int partition(int[] arr, int start, int end) {int index = start;int pivot = arr[index];int left = start, right = end;while (left < right) {// 让right找比pivot小的数while (right > left && arr[right] >= pivot) {right--;}// 让left找比pivot大的数while (left < right && arr[left] <= pivot) {left++;}// 让left与right这两个数进行交换swap(arr, left, right);}// 将基准值放到合适的位置swap(arr, index, left);// 返回基准下标return left;
}private static void swap(int[] nums, int left, int right) {int tmp = nums[left];nums[left] = nums[right];nums[right] = tmp;
}填坑法
【推荐】单函数法
代码量最少，且不需要swap函数；
public static void quickSort(int[] arr, int start, int end) {if (start >= end) {return;}int idx = start;int pivot = arr[idx];int left = start, right = end;while (left < right) {while (left < right && arr[right] >= pivot) {right--;}arr[left] = arr[right];while(left < right && arr[left] <= pivot) {left++;}arr[right] = arr[left];}// 从此行开始，left == rightarr[left] = pivot;if (start < left) {quickSort(arr, start, left - 1);}if (right < end) {quickSort(arr, right + 1, end);}
}
双函数法
/*** 快速排序* <p>* 这一层的逻辑基本不会变，注意递归退出条件** @param nums* @param start* @param end*/
public static void quickSort(int[] nums, int start, int end) {if (start < end) {int index = partition(nums, start, end);quickSort(nums, start, index - 1);quickSort(nums, index + 1, end);}
}/*** 填坑法** @param arr* @param start* @param end* @return*/
public static int partition(int[] arr, int start, int end) {int index = start;int pivot = arr[index];int left = start, right = end;while (left < right) {// 找到一个比基准小的值while (left < right && arr[right] >= pivot) {right--;}// 放到左边arr[left] = arr[right];// 找到一个比基准大的值while (left < right && arr[left] <= pivot) {left++;}// 放到右边arr[right] = arr[left];}// 基准放到位置上arr[left] = pivot;return left;
}
参考文档
快速排序（三）——hoare法
https://blog.csdn.net/fax_player/article/details/135719674
快速排序（四）——挖坑法，前后指针法与非递归
https://blog.csdn.net/fax_player/article/details/135750747
七大排序算法——快速排序，通俗易懂的思路讲解与图解(完整Java代码)
https://blog.csdn.net/The_emperoor_man/article/details/131706776
