Submission #513878

#	Time	Username	Problem	Language	Result	Execution time	Memory
513878		couplefire	Tents (JOI18_tents)	C++17	100 / 100	223 ms	35620 KiB

tents

#include <bits/stdc++.h>
using namespace std;

const int N = 3005;
const int MOD = 1000000007;

inline int add(int a, int b){return (a+b>=MOD)?a+b-MOD:a+b;}
inline void inc(int& a, int b){a = add(a, b);}
inline int sub(int a, int b){return (a-b<0)?a-b+MOD:a-b;}
inline void dec(int &a, int b){a = sub(a, b);}
inline int mul(int a, int b){return 1ll*a*b%MOD;}
inline void grow(int &a, int b){a = mul(a, b);}

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

int main(){
    // freopen("a.in", "r", stdin);
    cin.tie(0)->sync_with_stdio(0);
    cin >> n >> m;
    for(int i = 0; i<=n; ++i)
        for(int j = 0; j<=m; ++j){
            if(i==0 || j==0)
                {dp[i][j] = 1; continue;}
            // no take - 0
            inc(dp[i][j], dp[i][j-1]);
            // no take - 1
            if(i>=2) inc(dp[i][j], mul(dp[i-1][j-1], 4*i-4));
            // no take - 2
            if(i>=3) inc(dp[i][j], mul(dp[i-2][j-1], (i-1)*(i-2)/2));
            // no take - 2*
            if(i>=2 && j>=2) inc(dp[i][j], mul(dp[i-1][j-2], (i-1)*(j-1)));
            // take - 0 0
            inc(dp[i][j], mul(dp[i-1][j-1], 4));
            // take - 1 0
            if(i>=2) inc(dp[i][j], mul(dp[i-2][j-1], i-1));
            // take - 0 1
            if(j>=2) inc(dp[i][j], mul(dp[i-1][j-2], j-1));
        }
    cout << sub(dp[n][m], 1) << '\n';
}

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