1 void mergeSort(vector<int>& nums,int start,int end){
 2         if(start<end){
 3              int q = (start+end)/2;
 4              mergeSort(nums,start,q);
 5              mergeSort(nums,q+1,end);
 6              merge(nums,start,q,end);
 7         }
 8     }
 9 void merge(vector<int>& nums,int start,int q,int end){
10         vector<int> L1(q-start+1,0);
11         vector<int> L2(end-q,0);
12         L1.assign(nums.begin()+start,nums.begin()+q+1);
13         L2.assign(nums.begin()+q+1,nums.begin()+end+1);
14         int i=0,j=0;
15         for(int k = start;k<=end;k++){
16             if(L1[i] <= L2[j]){
17                 nums[k] = L1[i];
18                 i++;
19             }else{
20                 nums[k] = L2[j];
21                 j++;
22             }
23             if(i>L1.size()-1){
24                 for(int s = k+1;s<=end;s++){
25                     nums[s] = L2[j];
26                     j++;
27                 }
28                 break;
29             }
30             if(j>L2.size()-1){
31                 for(int s = k+1;s<=end;s++){
32                     nums[s] = L1[i];
33                     i++;
34                 }
35                 break;
36             }
37         }
38     }

 void quickSort(vector<int>& nums,int start,int end){
         int pivot;
         if(start<end){
             pivot = randPartition(nums,start,end);
             quickSort(nums,start,pivot-1);
             quickSort(nums,pivot+1,end);
         }
     }
  int randPartition(vector<int>& nums,int start ,int end){
         int randi = start;
         std::swap(nums[randi],nums[start]);
         int pivot = nums[start];
         int i = start;
         for(int j = start+1;j<=end;j++){
                if(nums[j]<pivot){
                    i++;
                    swap(nums[i],nums[j]);
                }
            }
            swap(nums[start],nums[i]);
            return i;
        }