Submission #887907

#	Time	Username	Problem	Language	Result	Execution time	Memory
887907		vjudge1	Tents (JOI18_tents)	C++17	100 / 100	56 ms	71040 KiB

tents

//In His Name
#include <bits/stdc++.h>
//#pragma GCC optimization("O3")
//#pragma GCC optimize("unroll-loops")
//#pragma GCC target("avx2")
using namespace std;
#define ll long long
#define int ll
typedef pair<int, int> pii;
#define F first
#define S second
#define pb push_back
#define bug(x) cout << "Ah shit , here we go again : " << x <<endl
#define all(x) x.begin() , x.end()
const int maxn = 3e3 + 10, MOD = 1e9 + 7;
const ll INF = 1e18;

int n , m , dp[maxn][maxn];

int32_t main(){
    ios_base::sync_with_stdio(false);

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

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