LeetCode/com/zerroi/leetcode/sort/QuickSort.java

package com.zerroi.leetcode.sort;


public class QuickSort {
    public static void main(String[] args) {
        QuickSortImpl quickSort = new QuickSortImpl();
        int[] arr = {5, 1, 2, 6, 78, 1, 8, 45, 1, 645, 12};
        int[] res = quickSort.quickSort(arr, 0, arr.length - 1);
        for (int re : res) {
            System.out.println(re);
        }
    }
}
class QuickSortImpl {

    public int[] quickSort(int[] arr, int left, int right) {
        if (left < right) {
            int partition = partition(arr, left, right);
            quickSort(arr, left, partition - 1);
            quickSort(arr, partition + 1, right);
        }
        return arr;
    }

    /* 元素交换 */
    void swap(int[] nums, int i, int j) {
        int tmp = nums[i];
        nums[i] = nums[j];
        nums[j] = tmp;
    }

    /* 哨兵划分 */
    int partition(int[] nums, int left, int right) {
        // 以 nums[left] 为基准数
        int i = left;
        int j = right;
        while (i < j) {
            while (i < j && nums[left] >= nums[j]) {
                j--;
            }
            while (i < j && nums[left] <= nums[i]) {
                i++;
            }
            swap(nums, i, j);
        }
        swap(nums, i, left);
        return i;
    }
}