Submission #2663719

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Source Code Expand

#include <bits/stdc++.h>
#define int long long
#define r(i,n) for(int i=0;i<n;i++)
using namespace std;

int dp[2][333][333],ans,n,m;
int mod=1000000007;

signed main(){
  cin>>n>>m;
  dp[0][1][1]=1;
  for(int i=0;i<m;i++){
    for(int j=0;j<=n;j++){
      for(int k=0;k<=n;k++){
        dp[(i+1)%2][j+1][k]+=dp[i%2][j][k]*(n-j);
        dp[(i+1)%2][j][j]+=dp[i%2][j][k]*k;
        dp[(i+1)%2][j][k]+=dp[i%2][j][k]*(j-k);

        dp[(i+1)%2][j+1][k]%=mod;
        dp[(i+1)%2][j][j]%=mod;
        dp[(i+1)%2][j][k]%=mod;
      }
    }
    r(k,333)r(j,333)dp[i%2][k][j]=0;
  }
  cout<<dp[m%2][n][n]<<endl;
}

Submission Info

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