Submission #5428284

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Source Code Expand

#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef vector<ll> vl;
typedef long double ld;
typedef vector<ld> vd;
typedef bool bl;
typedef vector<bl> vb;
typedef unordered_map<ll,unordered_map<ll,ll>> graph;

const ll e5 = 1 << 20;
const ll mod = 1000000007;
const ll e3 = 1 << 13;
const ll INF = 1ll << 60;

ll n,m;
ll dp[302][302][302];

int main(){
  cin >> n >> m;
  dp[0][1][1] = 1;
  for(ll i = 0;i < m;i++){
    for(ll j = 1;j <= n;j++){
      for(ll k = 1;k <= n;k++){
        dp[i][j][k] %= mod;
        dp[i+1][j+1][k] += dp[i][j][k]*(n-j);
        dp[i+1][j][k] += dp[i][j][k]*(j-k);
        dp[i+1][j][j] += dp[i][j][k]*k;
      }
    }
  }
  cout << dp[m][n][n]%mod << endl;
}

Submission Info

Judge Result