Submission #101331

#	Time	Username	Problem	Language	Result	Execution time	Memory
101331		Rudy420	Tents (JOI18_tents)	C++17	48 / 100	2045 ms	596 KiB

tents

#include <bits/stdc++.h>
using namespace std;
#define x first
#define y second
#define ll long long
#define pi pair<int,int>
#define pl pair<ll,ll>
#define pd pair<double,double>
#define ld long double
#define pld pair<ld,ld>
#define lg length()
#define sz size()
#define vi vector<int>
#define vl vector<ll>
#define vp vector<pi>
#define vpl vector<pl>
#define pb push_back
#define INF 1000000005
#define LINF 1000000000000000005

ll fact[6005],inv[6005],mod=1e9+7,ans,pw[6005],ip[6005];

ll pwr(ll a, ll p){
    if(!p) return 1;
    ll t=pwr(a,p/2);
    t*=t; t%=mod;
    if(p%2) t*=a, t%=mod;
    return t;
}

int n,m;


int32_t main(){
    /*seed_seq seq{
        (uint64_t) chrono::duration_cast<chrono::nanoseconds>(chrono::high_resolution_clock::now().time_since_epoch()).count(),
        (uint64_t) __builtin_ia32_rdtsc(),
        (uint64_t) (uintptr_t) make_unique<char>().get()
    };
    mt19937 rng(seq);*/
    ios_base :: sync_with_stdio(0); cin.tie(); cout.tie();
#ifdef LOCAL_DEFINE
    ifstream cin("input.in");
#endif

    fact[0]=inv[0]=pw[0]=ip[0]=1;
    for(int i=1;i<=6000;i++){
        fact[i]=fact[i-1]*i%mod;
        inv[i]=pwr(fact[i],mod-2);
        pw[i]=pw[i-1]*2%mod;
        ip[i]=pwr(pw[i],mod-2);
    }

    cin >> n >> m;
    for(int i=0;i<=n;i++){
        for(int j=0;j<=n-2*i && j<=m-i;j++){
            for(int k=0;k<=n-2*i-j && k<=m-i-2*j;k++){
                if(i+j+k){
                    ans+=fact[n]*fact[m]%mod*inv[n-2*i-j-k]%mod*inv[m-i-2*j-k]%mod*inv[i]%mod*inv[j]%mod*inv[k]%mod*ip[i]%mod*ip[j]%mod*pw[2*k]%mod;
                    ans%=mod;
                }
            }
        }
    }
    cout << ans;

}

• Subtask 1: 48 / 48
• Subtask 2: 0 / 52