Submission #407284

#	Time	Username	Problem	Language	Result	Execution time	Memory
407284		soroush	Zapina (COCI20_zapina)	C++17	110 / 110	162 ms	1520 KiB

zapina

//叫んで 藻掻もがいて 瞼まぶたを腫らしても
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef long double ld;
typedef pair<int , int> pii;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

const int maxn = 400;
const ll mod = 1e9+7;

#define pb push_back
#define endl '\n'
#define dokme(x) cout << x , exit(0)
#define ms(x , y) memset(x , y , sizeof x)
ll pw(ll a, ll b, ll md = mod){ll res = 1;while(b){if(b&1){res=(a*res)%md;}a=(a*a)%md;b>>=1;}return(res);}

ll n , ans , fact[maxn] , inv[maxn] , dp[maxn][maxn];

ll C(ll r , ll n){
	return ((fact[n] * inv[r])%mod * inv[n - r])%mod;
}

int32_t main(){
	ios::sync_with_stdio(false),cin.tie(0),cout.tie(0);
	cin >> n;
	ans = pw(n , n);
	fact[0] = inv[0] = 1;
	for(int i = 1 ; i < maxn ; i ++)
		fact[i] = (fact[i - 1] * i) % mod , inv[i] = pw(fact[i] , mod - 2);
	dp[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] = (dp[i][j] + dp[i-1][j-k] * C(k , n - j + k))%mod;
	cout << (ans - dp[n][n] + mod)%mod;
	return(0);
}

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