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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. typedef long long int ll;
  5.  
  6. int main() {
  7.     int n;
  8.     cin >> n;
  9.  
  10.     vector<ll> A(n);
  11.     for (int i = 0; i < n; i++) {
  12.         cin >> A[i];
  13.     }
  14.  
  15.     ll target;
  16.     cin >> target;
  17.  
  18.  
  19.    ll count =0;
  20.  
  21.    unordered_map<ll, ll> mpp;
  22.  
  23.    for(int j=0;j<n ;j++){
  24.    	int r1= A[j]+target;
  25.    	int r2= A[j]- target;
  26.  
  27.    	if(target==0)
  28.    	count+=mpp[r1];
  29.  
  30.    	else{
  31.    		count+= mpp[r1];
  32.    		count+= mpp[r2];
  33.    	}
  34.  
  35.    	mpp[A[j]]++;
  36.  
  37.    }
  38.    cout<<count<<endl;
  39.  
  40.     return 0;
  41. }
Success #stdin #stdout 0s 5312KB
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https://ideone.com/Z23h7U
language:
C++ (gcc 8.3)
created:
16 hours ago
visibility:
public

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