Submission #1161788

#	Time	Username	Problem	Language	Result	Execution time	Memory
1161788		MPG	Tents (JOI18_tents)	C++20	100 / 100	194 ms	58780 KiB

tents

//#pragma GCC optomize("Ofast")
#pragma GCC optimize("unroll-loops")
//#pragma GCC optimize("O3")
//#pragma GCC target("avx2")
//#pragma GCC target("sse,sse2,sse4.1,sse4.2") 



#include <bits/stdc++.h>
using namespace std;
typedef long long       ll;
#define     max_heap priority_queue<pair <ll, pair <ll, ll>>>
#define     min_heap priority_queue<pair <ll, ll>, vector<pair <ll, ll>>, greater<pair <ll, ll>>>
#define     sariE cin.tie(NULL); cout.tie(NULL); ios_base::sync_with_stdio(false);
#define     filE freopen("in.txt", "r", stdin); freopen("out1.txt", "w", stdout); 
#define     endl '\n'
#define     md(a) (a % mod + mod) % mod
#define     pb push_back
//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
//cout << setprecision(5) << fixed << f;
//hash prime = 769


ll const maxn = 2e5 + 123;
ll const inf = 2e18;
ll const loG = 23;
ll const mod = 1e9 + 7;
//ll const mod = 998244353;
ll const sq = 500;
ll power(ll a, ll b, ll mod){if(b==0)return 1;if(b==1)return a;ll x = power(a, b / 2, mod);return (((x * x) % mod) * (b % 2 ? a : 1)) % mod;}



ll n, m, dp[3001][3001];

ll f(ll n, ll m){
    if ((n <= 0) || (m <= 0))
        return 1;
    if ((dp[n][m] != 0))
        return dp[n][m];
    
    ll ret = f(n - 1, m);
    
    ll x = (f(n - 1, m - 1) * 4 * m) % mod;
    ret = (ret + x) % mod;

    ll y = 0;
    if (n > 1)
        y = f(n - 2, m - 1);
    x = (((m * (n - 1)) % mod) * y) % mod;
    ret = (ret + x) % mod;

    y = 0;
    if (m > 1)
        y = f(n - 1, m - 2);
    x = (((m * (m - 1) / 2) % mod) * y) % mod;
    ret = (ret + x) % mod;

    //cout << n << ' ' << m << ' ' << ret << endl;
    return dp[n][m] = ret;
}


void Solve(){

cin >> n >> m;
cout << md(f(n, m) - 1) << endl;




}





int main(){
sariE;// filE;



int test = 1;
//cin >> test;
while (test--) Solve();
return 0;
}

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