插入排序

   //插入排序1
    public static void insertSort1(int[] arr) {
      if (arr == null || arr.length < 2) {
            return;
        }
        int N = arr.length;
        for (int end = 1; end < N; end++) {
            int num = end;
            while (num - 1 >= 0 && arr[num - 1] > arr[num]) {
                swap(arr, num - 1, num);
                num--;
            }
        }
    }

    //插入排序2
    public static void insertSort2(int[] arr) {
        if (arr == null || arr.length < 2) {
            return;
        }
        int N = arr.length;
        for (int end = 1; end < N; end++) {
            for (int i = end - 1; i >= 0 && arr[i] > arr[i + 1]; i--) {
                swap(arr, i, i + 1);
            }
        }
    }

    public static void swap(int[] arr, int i, int j) {
        int tmp = arr[i];
        arr[i] = arr[j];
        arr[j] = tmp;
    }
    // for test
      public static void main(String[] args) {
        int[] a = new int[]{68947, 9, 2, 3, 72, 241, 6436, 2, 1};
        //insertSort1(a);
        insertSort2(a);
        System.out.println(Arrays.toString(a));
    }