Submission #917928

#	Time	Username	Problem	Language	Result	Execution time	Memory
917928		Equinox	Tents (JOI18_tents)	C++17	100 / 100	61 ms	71120 KiB

tents

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef pair<double,double> pdd;
//typedef complex<double> cpx;
#define fastio cin.tie(0)->sync_with_stdio(0); cout.tie(0);
#define all(x) x.begin(),x.end()
#define compress(x) x.erase(unique(all(x)),x.end())
#define ff first
#define ss second
#define INF 1e17
#define MAX 500010
#define SIZE 10010
#define MOD 1000000007

const ll mod = 1e9+7LL;

ll n,m,dp[3010][3010];

int main(){
    fastio;
    cin >> n >> m;
    dp[0][0] = 1;
    for(int i=1;i<=3000;i++){
        dp[0][i] = 1;
        dp[i][0] = 1;
    }
    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++){
            dp[i][j] = dp[i-1][j];
            dp[i][j] += 4*j*dp[i-1][j-1]; dp[i][j] %= mod;
            if(j>=2) dp[i][j] += j*(j-1)/2*dp[i-1][j-2];
            dp[i][j] %= mod;
            if(i>=2) dp[i][j] += (i-1)*j*dp[i-2][j-1];
            dp[i][j] %= mod;
        }
    }
    cout << dp[n][m]-1;
}

• Subtask 1: 48 / 48
• Subtask 2: 52 / 52