Submission #84378

#	Time	Username	Problem	Language	Result	Execution time	Memory
84378		Alexa2001	Tents (JOI18_tents)	C++17	100 / 100	228 ms	36056 KiB

tents

#include <bits/stdc++.h>

using namespace std;

const int Mod = 1e9 + 7, Nmax = 3003;
typedef long long ll;

int inm(int x, int y) { return (ll)x*y%Mod; }
void add_to(int &x, int y) { x+=y; if(x>=Mod) x-=Mod; }

int n, m, i, j, dp[Nmax][Nmax];

int main()
{
  //  freopen("input", "r", stdin);
    cin.sync_with_stdio(false);

    cin >> n >> m;
    for(i=0; i<=n || i<=m; ++i) dp[0][i] = dp[i][0] = 1;

    for(i=1; i<=n; ++i)
        for(j=1; j<=m; ++j)
        {
            dp[i][j] = dp[i-1][j];

            if(j>=2) add_to(dp[i][j], inm(dp[i-1][j-2], j*(j-1)/2));
            if(i>=2) add_to(dp[i][j], inm(dp[i-2][j-1], (i-1) * j));

            add_to(dp[i][j], inm(4 * j, dp[i-1][j-1]));
        }

    add_to(dp[n][m], Mod-1);
    cout << dp[n][m] << '\n';
    return 0;
}

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