Submission #948074

#	Time	Username	Problem	Language	Result	Execution time	Memory
948074		KiaRez	NoM (RMI21_nom)	C++17	100 / 100	332 ms	43440 KiB

Main

/*
    IN THE NAME OF GOD
*/
#include <bits/stdc++.h>

// #pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
// #pragma GCC optimize("O3")
// #pragma GCC optimize("unroll-loops")

using namespace std;

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

#define F                                      first
#define S                                      second
#define Mp                                     make_pair
#define pb                                     push_back
#define pf                                     push_front
#define size(x)                                ((ll)x.size())
#define all(x)                                 (x).begin(),(x).end()
#define kill(x)		                           cout << x << '\n', exit(0);
#define fuck(x)                                cout << "(" << #x << " , " << x << ")" << endl
#define endl                                   '\n'

const int N = 1e5+23, lg = 18;
ll Mod = 1e9+7; //998244353;

inline ll MOD(ll a, ll mod=Mod) {a%=mod; (a<0)&&(a+=mod); return a;}
inline ll poww(ll a, ll b, ll mod=Mod) {
    ll ans = 1;
    a=MOD(a, mod);
    while (b) {
        if (b & 1) ans = MOD(ans*a, mod);
        b >>= 1;
        a = MOD(a*a, mod);
    }
    return ans;
}

ll n, m, ifact[N], fact[N], dp[4005][4005], sz[N];

ll C(ll r, ll k) {
	if(r<0 || r>k) return 0;
	return MOD(fact[k] * MOD(ifact[r] * ifact[k-r]));
}

int main () {
	ios_base::sync_with_stdio(false), cin.tie(0);
	
	cin>>n>>m;
	fact[0] = ifact[0] = 1; 
	for(ll i=1; i<N; i++) {
		fact[i] = MOD(fact[i-1] * i);
		ifact[i] = poww(fact[i], Mod-2);
	}
	
	for(int i=1; i<=m; i++) sz[i] = (2*n-i+1+m-1)/m;

	ll ans = 0;

	for(int j=0; j<=m; j++) dp[0][j] = 1;
	for(int i=1; i<=n; i++) {
		for(ll j=1; j<=m; j++) {
			for(ll num=0; num<=i&&2*num<=sz[j]; num++) {
				dp[i][j] = MOD(dp[i][j] + dp[i-num][j-1]*MOD(C(num,i) * MOD(fact[2*num]*C(2*num,sz[j]))));
			}
		}
	}

	for(ll j=0; j<=n; j++) {
		ll res = MOD(C(j,n)*dp[j][m])*fact[2*n-2*j];
		if(j%2==0) ans = MOD(ans + res);
		else ans = MOD(ans - res);
	}

	cout<<ans<<endl;

	return 0;
}

• Subtask 1: 9 / 9
• Subtask 2: 12 / 12
• Subtask 3: 13 / 13
• Subtask 4: 18 / 18
• Subtask 5: 48 / 48