Submission #7447632

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Source Code Expand

#include <bits/stdc++.h>
using namespace std;
using Int = long long;
const Int MOD = 1000000007;
Int dp[301][301][301];
int main() {
    int N, M; 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 <= j; k++) {
                if (j + 1 <= N) 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;
            }
        }
        for (int j = 0; j <= N; j++) {
            for (int k = 0; k <= j; k++) {
                dp[i+1][j][k] %= MOD;
            }
        }
    }
    cout << dp[M][N][N] << '\n';
    return 0;
}

Submission Info

Judge Result