제출 #813959

#	제출 시각	아이디	문제	언어	결과	실행 시간	메모리
813959		kebine	Tents (JOI18_tents)	C++17	100 / 100	111 ms	70868 KiB

tents

#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ld long double
#define ull unsigned long long
#define pii pair<int, int>
#define pll pair<ll, ll>
#define fi first
#define se second

const int N = 3e3 + 5;
const int mod = 1e9 + 7;

ll dp1[N][N], dp2[N];

int main() { 
    ios_base::sync_with_stdio(false); cin.tie(NULL);
    int h, w;
    cin >> h >> w;
    dp1[0][w] = 1;
    for (int i = 0; i < h; i++) {
        for (int j = w; j >= 0; j--) {
            if (j >= 2) {
                dp1[i + 1][j - 2] += ((j * (j - 1) / 2) % mod) * dp1[i][j];
                dp1[i + 1][j - 2] %= mod;
            }
            if (j >= 1) {
                dp1[i + 1][j - 1] += j * dp2[j] + 4 * j * dp1[i][j]; 
                dp1[i + 1][j - 1] %= mod;
            }
            dp1[i + 1][j] += dp1[i][j];
            dp1[i + 1][j] %= mod;
            dp2[j] += (i + 1) * dp1[i][j] - i * dp1[max(i - 1, 0)][j];
            dp2[j] %= mod;
        }
    }
    ll ans = 0;
    for (int i = 0; i < w; i++) {
        ans += dp1[h][i];
        ans %= mod;
    }
    cout << ans << "\n";
    // for (int i = 0; i <= h; i++) {
    //     for (int j = w; j >= 0; j--) cout << dp1[i][j] << " ";
    //     cout << "\n";
    // }
}  

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