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  1. #include <bits/stdc++.h>
  2. #define fi first
  3. #define se second
  4. #define ll long long
  5. #define N int(1e6)
  6. using namespace std;
  7. unordered_map<ll,ll>cnt,cnt1;
  8. ll n,ans;
  9. pair<ll,ll>a[N+10];
  10. int main()
  11. {
  12.     ios::sync_with_stdio(0);
  13.     cin.tie(0);
  14.     cout.tie(0);
  15.  
  16.     cin>>n;
  17.     for(int i=1;i<=n;i++)
  18.     {
  19.         cin>>a[i].fi>>a[i].se;
  20.         cnt[a[i].fi]++;
  21.         cnt1[a[i].se]++;
  22.     }
  23.     for(int i=1;i<=n;i++)
  24.     {
  25.         ll x1=cnt[a[i].fi]-1;
  26.         ll y1=cnt1[a[i].se]-1;
  27.         //cout<<a[i].fi<<" "<<a[i].se<<" "<<x1<<" "<<y1<<'\n';
  28.         ans+=x1*y1;
  29.     }
  30.     cout<<ans;
  31.  
  32.  
  33.     return 0;
  34. }
  35.  
  36.  
Success #stdin #stdout 0s 5324KB
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https://ideone.com/dwhq6K
language:
C++ (gcc 8.3)
created:
6 hours ago
visibility:
public

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