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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3.  
  4. const int N=1e6+6, mod=1e9+7;
  5. int n, a[N], x;
  6. long long ans;
  7. map<long long, long long> mp;
  8.  
  9. signed main()
  10. {
  11.     ios::sync_with_stdio(0);
  12.     cin.tie(0); cout.tie(0);
  13.  
  14.     cin >> n >> x;
  15.     for(int i=1;i<=n;++i) cin >> a[i];
  16.     for(int i=1;i<=n;++i){
  17.         ans+=mp[a[i]*1LL-x]+mp[a[i]*1LL+x];
  18.         ans%=mod;
  19.         mp[a[i]]=(mp[a[i]]+1)%mod;
  20.     }
  21.     cout << ans;
  22.     return 0;
  23. }
  24.  
Success #stdin #stdout 0.01s 5280KB
comments (?)
stdin 
Standard input is empty
stdout 
Standard output is empty
https://ideone.com/Q0Yyur
language:
C++14 (gcc 8.3)
created:
11 days ago
visibility:
public

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