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  1. #include <bits/stdc++.h>
  2.  
  3. using namespace std;
  4.  
  5. #define modulo ll (1e9 + 7)
  6. #define neig(a, u, e, v) for(int v, e = (a).head[u] ; ~e and (v = (a).to[e], 1) ; e = (a).nxt[e])
  7.  
  8. typedef long long ll;
  9.  
  10. const int N = 2e5 + 9, M = 1e6 + 9, OO = 0x3f3f3f3f;
  11. const ll llOO = 0x3f3f3f3f3f3f3f3f;
  12.  
  13. int main() {
  14.     cin.tie(0);
  15.     cin.sync_with_stdio(0);
  16.  
  17.     int n;
  18.     cin >> n;
  19.  
  20.     ll x;
  21.     cin >> x;
  22.  
  23.     int a[n];
  24.     for(int i = 0;i < n;i++)
  25.         cin >> a[i];
  26.  
  27.     int ans = 0; // number of subsets with sum equal to x
  28.  
  29.     // the binary representation of i represents the subset
  30.     for(int i = 0;i < (1 << n);i++){
  31.         ll sum = 0;// subset sum
  32.         for(int j = 0;j < n;j++){
  33.             // check if the j-th bit of i is 1 (j-th element is included in the subset)
  34.             if((i >> j) & 1){
  35.                 sum += a[j];
  36.             }
  37.         }
  38.  
  39.         if(sum == x)
  40.             ans++;
  41.     }
  42.  
  43.     cout << ans;
  44. }
Success #stdin #stdout 2.01s 5384KB
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https://ideone.com/fTUiev
language:
C++14 (gcc 8.3)
created:
4 years ago
visibility:
public

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