1、快速排序

public class Sort {
    public static void main(String[] args) {
        int[] arr = RandomUtil.randomInts(100);
        System.out.println(JSONObject.toJSON(arr));
        System.out.println();

        quickSort(arr, 0, arr.length - 1);
        System.out.println(JSONObject.toJSON(arr));
    }

    /**
     * 快速排序
     * @param arr
     * @param left
     * @param right
     */
    public static void quickSort(int[] arr, int left, int right) {
        int l = left;
        int r = right;
        int midValue = arr[(left + right) / 2];
        int temp = 0;

        //左边比右边小，可以排序
        while (l < r) {
            while (arr[l] < midValue) {
                l++;
            }
            while (arr[r] > midValue) {
                r--;
            }
            if (l >= r) break;
            temp = arr[r];
            arr[r] = arr[l];
            arr[l] = temp;

            if (arr[l] == midValue) {
                r++;
            }
            if (arr[r] == midValue) {
                l--;
            }
        }

        //如果左边等于右边，手动移动
        if (l == r) {
            l++;
            r--;
        }

        if (l < right) {
            quickSort(arr, l, right);
        }
        if (r > left) {
            quickSort(arr, left, r);
        }
    }