【算法】快速排序

QuickSort.java

    private void quickSort(int[] arr, int low, int high) {
        if (low < high) {
            int first = low;
            int last = high;
            int key = arr[low];
            while (first < last) {
                while (first < last && key <= arr[last]) {
                    last--;
                }
                // 将比第一个小的放到首端
                arr[first] = arr[last];

                while (first < last && key >= arr[first]) {
                    first++;
                }
                // 将比第一个大的放到末端
                arr[last] = arr[first];
            }
            arr[first] = key;
            quickSort(arr, low, first - 1);
            quickSort(arr, first + 1, high);
        }
    }