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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. int main() {
  5.     int n,k; cin>>n>>k;
  6.     int f = 0;
  7.     int mp[k] = {};
  8.     for(int i=0;i<n;i++) {
  9.         int t;
  10.         cin>>t;
  11.         t %= k;
  12.         f += mp[(k-t)%k];
  13.         mp[t]++;
  14.     }
  15.     cout << f;
  16. }
Success #stdin #stdout 0s 5316KB
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6 5
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5
https://ideone.com/ME1KH7
7
language:
C++14 (gcc 8.3)
created:
8 hours ago
visibility:
public

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