Submission #319566

#TimeUsernameProblemLanguageResultExecution timeMemory
319566BeanZZapina (COCI20_zapina)C++14
0 / 110
1 ms364 KiB
// I_Love_LPL #include <bits/stdc++.h> using namespace std; //#define task "A" #define ll long long #define endl '\n' const int N = 355; const int mod = 1e9 + 7; const int lg = 18; ll dp[N][N][2]; ll fact[N], f[N][N]; ll binpow(ll u, ll p){ if (p == 0) return 1; if (p == 1) return u; ll t = binpow(u, p / 2); if (p & 1) return t * t % mod * u % mod; return t * t % mod; } ll nCk(ll n, ll k){ return fact[n] * binpow(fact[n - k], mod - 2) % mod * binpow(fact[k], mod - 2) % mod; } int main(){ ios_base::sync_with_stdio(false); cin.tie(0); if (fopen(".inp", "r")){ freopen(".inp", "r", stdin); freopen(".out", "w", stdout); } ll n; cin >> n; fact[0] = 1; for (int i = 1; i <= (n + 1); i++){ fact[i] = fact[i - 1] * i % mod; } for (int i = 0; i <= (n + 1); i++){ for (int j = 0; j <= i; j++){ f[i][j] = nCk(i, j); } } dp[0][0][0] = 1; for (int i = 1; i <= n; i++){ for (int j = 0; j <= n; j++){ for (int k = 0; k <= j; k++){ dp[i][j][0] = (dp[i][j][0] + dp[i - 1][j - k][0] * f[n - (j - k)][k]) % mod; dp[i][j][1] = (dp[i][j][1] + dp[i - 1][j - k][1] * f[n - (j - k)][k]) % mod; if (k == i){ dp[i][j][1] = (dp[i][j][1] + dp[i - 1][j - k][0] * f[n - (j - k)][k]) % mod; } } } } cout << dp[n][n][1]; } /* */

Compilation message (stderr)

zapina.cpp: In function 'int main()':
zapina.cpp:26:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   26 |         freopen(".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~
zapina.cpp:27:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   27 |         freopen(".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~
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