제출 #1000465

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
1000465		PagodePaiva	캥거루 (CEOI16_kangaroo)	C++17	100 / 100	13 ms	31836 KiB

kangaroo

#include<bits/stdc++.h>
using namespace std;
#define int long long
#define tii tuple<int,int,int>
#define pii pair<int,int>
#define ff first
#define ss second
#define all(x) x.begin(),x.end()
#define allr(x) x.rbegin(),x.rend()
#define pb push_back
#define mp make_pair

const int maxn = 2e3+5, MOD=1e9+7;

int dp[maxn][maxn];

void solve(){
	int n,cs,cf; cin >> n >> cs >> cf;

	dp[0][0] = 1;
	for(int k=1; k<=n; k++){
		for(int c=1; c<=n; c++){
			int p = (k>cs)+(k>cf);

			// uniao (n_c2 - (k>cs) - (k>cf) jeitos) e criar (1 jeito)
			dp[k][c] = (dp[k-1][c+1]*(c*(c+1) -p*c+(k==n && c==1)) + dp[k-1][c-1])%MOD;

			if(k==min(cs,cf)){
				// extensao (c jeitos) e criar (1 jeito)
				dp[k][c] = (dp[k-1][c]*c + dp[k-1][c-1])%MOD;
			}
			if(k==max(cs,cf)){
				// extensao (c-1 jeitos) e criar (1 jeito)
				dp[k][c] = (dp[k-1][c]*(c-(k<n)) + dp[k-1][c-1])%MOD;
			}
			// cout << dp[k][c] << " ";
		}
		// cout << endl;
	}

	cout << dp[n][1] << '\n';
}

signed main(){
	ios_base::sync_with_stdio(false); cin.tie(0);
	int t=1;
	// cin >> t;
	while(t--){
		solve();
	}
}

• Subtask 1: 6 / 6
• Subtask 2: 30 / 30
• Subtask 3: 15 / 15
• Subtask 4: 49 / 49