Submission #1914351

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Source Code Expand

#include<bits/stdc++.h>
using namespace std;

#define int long long

#define rep(i,n) for(int i=0;i<(n);i++)
#define pb push_back
#define all(v) (v).begin(),(v).end()
#define fi first
#define se second
typedef vector<int>vint;
typedef pair<int,int>pint;
typedef vector<pint>vpint;

template<typename A,typename B>inline void chmin(A &a,B b){if(a>b)a=b;}
template<typename A,typename B>inline void chmax(A &a,B b){if(a<b)a=b;}

const int mod=1000000007;

int dp[2][333][333];
int N,M;

inline void add(int &a,int b){
    a+=b;
    if(a>=mod)a-=mod;
}

signed main(){
    cin>>N>>M;
    dp[0][1][0]=1;

    rep(i,M){
        rep(j,N+1){
            rep(k,N+1){
                if(dp[i&1][j][k]==0)continue;
                int o=N-j-k;
                add(dp[(i+1)&1][j][k+1],dp[i&1][j][k]*o%mod);
                add(dp[(i+1)&1][j][k],dp[i&1][j][k]*k%mod);
                add(dp[(i+1)&1][j+k][0],dp[i&1][j][k]*j%mod);
                dp[i&1][j][k]=0;
            }
        }
    }

    cout<<dp[M&1][N][0]<<endl;
    return 0;
}

Submission Info

Judge Result