Submission #2370007

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Source Code Expand

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

constexpr int mod = 1e9 + 7;

int main() {
  int n, m;
  cin >> n >> m;

  vector<vector<int64_t>> dp(334, vector<int64_t>(334, 0));
  dp[n - 1][1] = 1;

  for (int i = 0; i < m; ++i) {
    vector<vector<int64_t>> dp2(334, vector<int64_t>(334, 0));
    for (int j = 0; j < n; ++j) {
      for (int k = 1; k <= n; ++k) {
        (dp2[j][n - j] += k * dp[j][k] % mod) %= mod;
        if (j) (dp2[j - 1][k] += j * dp[j][k]) %= mod;
        (dp2[j][k] += (n - j - k) * dp[j][k]) %= mod;
      }
    }

    dp = dp2;
  }

  cout << dp[0][n] << endl;
}

Submission Info

Judge Result