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  1. #include <iostream>
  2. #include<bits/stdc++.h>
  3. using namespace std;
  4.  
  5.  void mergeHelp(vector<pair<int,int> >&store,int start,int mid,int end,vector<int>&ans){
  6.         vector<pair<int,int> >temp(end-start+1);
  7.  
  8.         int i=start,j=mid,k=0,cnt=0;
  9.         while(i<mid && j<=end){
  10.             if(store[i].first<=store[j].first){
  11.  
  12.                 ans[store[i].second]+=cnt;
  13.                 temp[k++]=store[i++];
  14.  
  15.             }else{
  16.  
  17.                 temp[k++]=store[j++];
  18.                 cnt++;
  19.             }
  20.  
  21.         }
  22.  
  23.         while(i<mid){
  24.             ans[store[i].second]+=cnt;
  25.             cout<<"store:"<<store[i].first<<endl;
  26.             temp[k++]=store[i++];
  27.  
  28.         }
  29.  
  30.         while(j<=end){
  31.             temp[k++]=store[j++];
  32.         }
  33.  
  34.         j=start;
  35.         for(int i=0;i<k;++i){
  36.  
  37.             store[j++]=temp[i];
  38.         //    cout<<" "<<store[j-1].first<<" ";
  39.         }
  40.         //cout<<endl;
  41.         return;
  42.  
  43.     }
  44.  
  45.     void countSmaller(vector<pair<int,int> >&store,int start,int end,vector<int>&ans){
  46.         if(start<end){
  47.             int mid=(start+end)/2;
  48.  
  49.             countSmaller(store,start,mid,ans);
  50.             countSmaller(store,mid+1,end,ans);
  51.  
  52.             mergeHelp(store,start,mid+1,end,ans);
  53.         }
  54.         return;
  55.     }
  56.  
  57.     vector<int> countSmaller(vector<int>& nums) {
  58.         int size=nums.size();
  59.         vector<pair<int,int> >store(size);
  60.         for(int i=0;i<size;++i){
  61.             store[i]=make_pair(nums[i],i);
  62.         }
  63.         vector<int>ans(size,0);
  64.         countSmaller(store,0,size-1,ans);
  65.         return ans;
  66.  
  67.     }
  68.  
  69.  
  70. int main() {
  71. 	vector<int>nums={5, 2, 6, 1};
  72. 	vector<int>ans=countSmaller(nums);
  73. 	for(int i=0;i<ans.size();++i){
  74. 		cout<<ans[i]<<" ";
  75. 	}
  76. 	return 0;
  77. }
Success #stdin #stdout 0s 3416KB
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stdin
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Standard input is empty
stdout
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store:5
store:6
2 1 1 0
https://ideone.com/IWx2Rp
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
secret

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