Submission #384494

#	Time	Username	Problem	Language	Result	Execution time	Memory
384494		BlancaHM	Easter Eggs (info1cup17_eastereggs)	C++14	0 / 100	2 ms	620 KiB

eastereggs

#include <iostream>
#include <vector>
#include <set>
#include <algorithm>
#include <queue>
#include "grader.h"
using namespace std;

void init(set<int> & islandsLeft, vector <pair<int,int>> & bridges, vector<vector<int>> & adj) {
	int N = (int) bridges.size()+1;
	for (int i = 0; i < N; i++) {
		islandsLeft.insert(i);
		if (i) {
			bridges[i - 1].first--;
			bridges[i - 1].second--;
			adj[bridges[i - 1].first].push_back(bridges[i - 1].second);
			adj[bridges[i - 1].second].push_back(bridges[i - 1].first);
		}
	}
}

vector<int> process(set<int> & curQ, set<int> & islandsLeft) {
	vector<int> queryVec, nextIs;
	for (auto it = curQ.begin(); it != curQ.end(); it++)
		queryVec.push_back(*it);
	if (query(queryVec)) {
		// islands = intersection of islands and curQ
		nextIs.clear();
		for (int is : islandsLeft) {
			if (curQ.find(is) != curQ.end())
				nextIs.push_back(is);
		}
	} else {
		// islands = intersection of islands and NOT curQ
		nextIs.clear();
		for (int is : islandsLeft) {
			if (curQ.find(is) == curQ.end())
				nextIs.push_back(is);
		}
	}
	return nextIs;
}

int findEgg(int N, vector <pair<int,int>> bridges) {
	vector<vector<int>> adj(N);
	vector<int> nextIs;
	set<int> islandsLeft, curQ;
	init(islandsLeft, bridges, adj);
	queue<int> q;
	while ((int) islandsLeft.size() > 1) {
		// hacemos un árbol que contenga la primera mitad de islas restantes y ninguna de la segunda mitad
		curQ.clear();
		curQ.insert(*islandsLeft.begin());
		q = queue<int>();
		q.push(*islandsLeft.begin());
		int islands = 1;
		while(q.size()) {
			if (islands*2 >= (int) islandsLeft.size())
				break;
			int curIs = q.front();
			q.pop();
			for (int v: adj[curIs]) {
				if (islands*2 >= (int) islandsLeft.size()) break;
				if (curQ.find(v) == curQ.end()) {
					curQ.insert(v);
					q.push(v);
					if (islandsLeft.find(v) != islandsLeft.end())
						islands++;
				}
			}
			if (islands*2 >= (int) islandsLeft.size()) break;
		}
		// process islandsLeft
		nextIs = process(curQ, islandsLeft);
		islandsLeft.clear();
		for (int is: nextIs) {
			islandsLeft.insert(is);
			//cout << is << ' ';
		}
		//cout << '\n';
	}
	return *islandsLeft.begin() + 1;
}

• Subtask 1: 0 / 40
• Subtask 2: 0 / 40
• Subtask 3: 0 / 20