Submission #1112034

#	Time	Username	Problem	Language	Result	Execution time	Memory
1112034		Icelast	Tents (JOI18_tents)	C++17	100 / 100	141 ms	70992 KiB

tents

#include <iostream>
#include <bits/stdc++.h>
#define ll long long
using namespace std;
const ll maxn = 2*1e5+5, INF = 4e18+9, mod = 1e9+7, inv2 = (mod+1)/2;
void solve(){
    int n, m;
    cin >> n >> m;
    vector<vector<ll>> f(n+1, vector<ll>(m+1, 0)); // consider problem FILL (not rectangle) from (1, 1) to (i, j)
    for(int i = 1; i <= n; i++) f[i][0] = 1;
    for(int j = 0; j <= m; j++) f[0][j] = 1;
    for(int i = 1; i <= n; i++){
        for(int j = 1; j <= m; j++){
            //nothing on ith row
            f[i][j] += f[i-1][j];
            //place one thing on ith row
            f[i][j] += f[i-1][j-1] * (j*4)%mod;
            //place 2 horizontally
            if(j-2 >= 0) f[i][j] += f[i-1][j-2] * (j*(j-1)%mod*inv2%mod)%mod;
            //place 2 vertically
            if(i-2 >= 0) f[i][j] += f[i-2][j-1] * (j*(i-1)%mod)%mod;
            f[i][j] %= mod;
        }
    }
    cout << f[n][m]-1;
}
int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    solve();
}

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