Submission #963073

#	Time	Username	Problem	Language	Result	Execution time	Memory
963073		anton	Star Trek (CEOI20_startrek)	C++17	7 / 100	1 ms	2652 KiB

startrek

#include<bits/stdc++.h>

using namespace std;
#define int long long

const int MAX_N = 1e5;
const int mod = 1e9+7;


vector<int> adj[MAX_N];
int pow2[64];

void precalc(){
    pow2[0] = 2;
    for(int i = 1; i<61; i++){
        pow2[i] = (pow2[i-1] * pow2[i-1])%mod;
    }
}

int mpow(int p){
    int res= 1;
    for(int i = 0; i<61; i++){
        if((1LL<<i)&p){
            res = (res*pow2[i])%mod;
        }
    }
    return res;
}



signed main(){
    int n, d;
    cin>>n>>d;
    for(int i = 0; i<n-1;i++){
        int a, b;
        cin>>a>>b;

        adj[a-1].push_back(b-1);
        adj[b-1].push_back(a-1);
    }

    precalc();


    int res= mpow(2*d);

    cout<<res<<endl;
    
}

• Subtask 1: 0 / 0
• Subtask 2: 7 / 7
• Subtask 3: 0 / 8
• Subtask 4: 0 / 15
• Subtask 5: 0 / 15
• Subtask 6: 0 / 20
• Subtask 7: 0 / 20
• Subtask 8: 0 / 15