class Solution {

 public:

     void merge(vector<int>& nums1, int m, vector<int>& nums2, int n) {

         vector<int> nums3(nums1);                  //挺好用，vector克隆

         int index1=,index2=,index3=;

         while(index2<n&&index3<m){

             if(nums2[index2]<=nums3[index3]){

                 nums1[index1++]=nums2[index2++];

             }

             else{

                 nums1[index1++]=nums3[index3++];

             }

         }

         while(index2<n){

             nums1[index1++]=nums2[index2++];

         }

         while(index3<m){

             nums1[index1++]=nums3[index3++];

         }

     }

 };