Submission #1001257

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Source Code Expand

using System;
using System.Text;
using System.Collections.Generic;
class Solve{
    int N,M;
    public Solve(){}
    StringBuilder sb;
    public static int Main(){
        new Solve().Run();
        return 0;
    }
    void Run(){
        sb = new StringBuilder();
        Read();
        Calc();
        Console.Write(sb.ToString());
    }
    void Calc(){
        long[,,] d = new long[M+1,N,N+1];
        for(int i=0;i<M+1;i++){
            for(int j=0;j<N;j++){
                for(int k=0;k<N+1;k++){
                    if(i == 0){
                        if(j == 0 && k == 0){
                            d[i,j,k] = 1;
                        }
                        else{
                            d[i,j,k] = 0;
                        }
                    }
                    else{
                        d[i,j,k] = 0;
                    }
                }
            }
        }
        for(int i=1;i<M+1;i++){
            for(int j=0;j<N;j++){
                for(int k=0;k<N+1;k++){
                    if(k != 0){
                        d[i,j,k] = (d[i,j,k] + (d[i-1,j,k] * (k-j-1) % Define.mod)) % Define.mod;
                        d[i,k-1,k] = (d[i,k-1,k] + (d[i-1,j,k] * (j+1) % Define.mod)) % Define.mod;
                    }
                    if(k != N){
                        if(k == 0){
                            d[i,j,k+1] = (d[i,j,k+1] + d[i-1,j,k]) % Define.mod;
                        }
                        else{
                            d[i,j,k+1] = (d[i,j,k+1] + (d[i-1,j,k] * (N-k) % Define.mod)) % Define.mod;
                        }
                    }
                }
            }
        }
        sb.Append(d[M,N-1,N]+"\n");
    }
    void Read(){
        string[] str = Console.ReadLine().Split(' ');
        N = int.Parse(str[0]);
        M = int.Parse(str[1])+1;
    }    
}
public static class Define{
    public const long mod = 1000000007;
}

Submission Info

Judge Result