Submission #319570

#	Time	Username	Problem	Language	Result	Execution time	Memory
319570		BeanZ	Zapina (COCI20_zapina)	C++14	110 / 110	199 ms	3428 KiB

zapina

// 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; i++){
        fact[i] = fact[i - 1] * i % mod;
    }
    for (int i = 0; i <= n; 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++){
                if (k == i){
                    dp[i][j][1] = (dp[i][j][1] + 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;
                } else {
                    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;
                }
            }
        }
    }
    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);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 22 / 22
• Subtask 2: 33 / 33
• Subtask 3: 55 / 55