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  1. #include <bits/stdc++.h>
  2. using namespace std;
  3. #define all(x) (x).begin(),(x).end()
  4. #define sz(x) (int)(x).size()
  5. #define FOR(i,a,b) for(int i=(a);i<=(b);++i)
  6. #define FORD(i,a,b) for(int i=(a);i>=(b);--i)
  7. #define pb push_back
  8. #define fi first
  9. #define se second
  10. #define el "\n"
  11. typedef long long ll;
  12. const ll MOD=1e9+7,INF=1e18;
  13. int n,mai[21][21],dp[1<<21];
  14. void solve(){
  15.     cin>>n;
  16.     for (int i=0;i<n;i++)
  17.     {
  18.         for (int j=0;j<n;j++)
  19.         {
  20.             cin>>mai[i][j];
  21.         }
  22.     }
  23.     dp[0]=1;
  24.     int nm=(1<<n);
  25.     for (int m=0;m<nm-1;m++)
  26.     {
  27.         if (dp[m]==0) continue;
  28.         int i=__builtin_popcount(m);
  29.         for (int j=0;j<n;j++)
  30.         {
  31.             if (mai[i][j]==1 and !(m&(1<<j)))
  32.             {
  33.                 int nx=m|(1<<j);
  34.                 dp[nx]+=dp[m];
  35.             }
  36.         }
  37.     }
  38.     cout<<dp[nm-1]<<el;
  39. }
  40.  
  41. int main(){
  42.     ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
  43.     int t=1;//cin>>t;
  44.     while(t--)solve();
  45.     return 0;
  46. }
  47.  
Success #stdin #stdout 0.01s 5324KB
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stdin 
Standard input is empty
stdout 
1
https://ideone.com/fR0Clc
language:
C++14 (gcc 8.3)
created:
10 hours ago
visibility:
public

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