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  1. #include <bits/stdc++.h>
  2. const int mod = 1e9+7;
  3. long long fp(long long b, int e){
  4.     if(e) return fp(b*b%mod, e>>1) * (e&1?b:1) % mod;
  5.     return 1;
  6. }
  7. signed main() {
  8.     std::ios_base::sync_with_stdio(false); std::cin.tie(nullptr);
  9.     int t;
  10.     std::cin >> t;
  11.     while(t--){
  12.         int n, q;
  13.         std::cin >> n >> q;
  14.         while(q--){
  15.             int x;
  16.             std::cin >> x;
  17.             long long p = 3;
  18.             long long ans = 2 * x * fp(p, mod-2) % mod;
  19.             for(int y =x+1; y <=n; ++y){
  20.                 p = p * 3 % mod;
  21.                 ans = (ans + y * fp(p, mod-2) % mod) % mod;
  22.             }
  23.             p = 3;
  24.             for(int y=x-1; y; --y){
  25.                 p = p * 3 % mod;
  26.                 ans = (ans + y * fp(p, mod-2) % mod) % mod;
  27.             }
  28.             std::cout << ans << '\n';
  29.         }
  30.     }
  31. }
Success #stdin #stdout 0.01s 5324KB
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https://ideone.com/rP6EfK
language:
C++14 (gcc 8.3)
created:
14 days ago
visibility:
public

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