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  1. #include<bits/stdc++.h>
  2. using namespace std;
  3. int countPairs(vector<int>&b,int k){
  4.     unordered_map<int,int>f;
  5.     int cnt=0;
  6.     for(int i=0;i<b.size();i++){
  7.         int req=b[i]-k;
  8.         if(f.find(req)!=f.end()){
  9.         	cnt+=f[req];
  10.         }
  11.         f[b[i]]++;
  12.     }
  13.     return cnt;
  14. }
  15. int main(){
  16.     vector<int>b={5,3,6,2,5};int k=2;
  17.     cout<<countPairs(b,k)<<"\n";
  18.     return 0;
  19. }
  20.  
Success #stdin #stdout 0.01s 5264KB
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https://ideone.com/iK4eXi
language:
C++ (gcc 8.3)
created:
4 days ago
visibility:
public

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