Submission #1233072

#	Time	Username	Problem	Language	Result	Execution time	Memory
1233072		LaMatematica14	Star Trek (CEOI20_startrek)	C++20	0 / 100	170 ms	327680 KiB

startrek

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

const long long mod = 1000000007;

int main() {
    long long N, D; cin >> N >> D;
    vector<vector<long long>> adj(N+1); // occhio 1-based
    for (long long  i = 0; i < N-1; i++) {
        long long u, v; cin >> u >> v;
        adj[u].push_back(v);
        adj[v].push_back(u);
    }

    vector<long long> pot(1000000);
    pot[0] = 1;
    for (int i = 1; i < 1000000; i++) pot[i] = (pot[i-1]*2)%mod; 

    function<long long(int)> rec = [&](int a) -> long long{
        if (a == 0) return 1;
        return ((rec(a-1)+pot[2*a-2])%mod)*2;
    };
    cout << rec(D)%mod << "\n";
}

• Subtask 1: 0 / 0
• Subtask 2: 0 / 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