Submission #1048824

#	Time	Username	Problem	Language	Result	Execution time	Memory
1048824		vjudge1	Easter Eggs (info1cup17_eastereggs)	C++17	100 / 100	14 ms	600 KiB

eastereggs

#include <bits/stdc++.h>
#include "grader.h"

using namespace std;
using ll = long long;

int findEgg (int _N, vector<pair<int, int>> bridges){
    int N = _N;
    vector<vector<int>> G(N + 5);
    for (pair<int, int>&x : bridges){
        int u = x.first, v = x.second;
        G[u].emplace_back(v);
        G[v].emplace_back(u);
    }
    vector<int> minDist(N + 5), rev(N + 5);
    queue<int> q;
    q.emplace(1);
    minDist[1] = 1; rev[1] = 1;
    int cnt = 1;
    while(q.size()){
        int u = q.front(); q.pop();
        for (int &v : G[u]){
            if (!minDist[v]){
                q.emplace(v);
                minDist[v] = ++cnt;
                rev[minDist[v]] = v;
            }
        }
    }
    auto check = [&](int x) -> bool{
        vector<int> node;
        for (int i = 1; i <= N; ++i) if(minDist[i] <= x){
            node.emplace_back(i);
        }
        return query(node);
    };
    int l = 1, r = N;
    while (l < r){
        int m = (l + r) >> 1;
        if(check(m)) r = m;
        else l = m + 1;
    }
    return rev[l];
}

• Subtask 1: 40 / 40
• Subtask 2: 40 / 40
• Subtask 3: 20 / 20