1. /**
    2.      * @desc 归并两个有序数组  lettcode #88
    3.      * 把归并结果存到第一个数组上
    4.      * Input:
    5.      * nums1 = [1,2,3,0,0,0], m = 3
    6.      * nums2 = [2,5,6],       n = 3
    7.      * Output: [1,2,2,3,5,6]
    8.      * 
    9.      * **/
    10.     function merge(nums1, m, nums2, n) {
    11.       let index1 = m - 1;
    12.       let index2 = n - 1;
    13.       let indexMerge = m + n - 1;
    14.       while (index1 >= 0 || index2 >= 0) {
    15.         if (index1 < 0) {
    16.           nums1[indexMerge--] = nums2[index2--];
    17.         } else if (index2 < 0) {
    18.           nums1[indexMerge--] = nums1[index1--];
    19.         } else if (nums1[index1] > nums2[index2]) {
    20.           nums1[indexMerge--] = nums1[index1--];
    21.         } else {
    22.           nums1[indexMerge--] = nums2[index2--]
    23.         }
    24.       }
    25.       console.log(nums1)
    26.     }
    27.     merge([1, 2, 3, 0, 0, 0], 3, [2, 5, 6], 3);