Submission #223740

#	Time	Username	Problem	Language	Result	Execution time	Memory
223740		staniewzki	Parachute rings (IOI12_rings)	C++17	100 / 100	921 ms	60888 KiB

rings

#include<bits/stdc++.h>
using namespace std;
 
#define REP(i, n) for(int i = 0; i < n; i++)
 
template<class T> int size(T && a) { return (int) a.size(); }

struct Graph {
	vector<int> rep, deg;
	int excluded = -1;

	int find(int x) {
		return rep[x] < 0 ? x : find(rep[x]);
	}

	int bicomp = -1;
	int get_cycle() {
		return -rep[find(bicomp)];
	}

	void join(int x, int y) {
		x = find(x), y = find(y);
		if(x == y) {
			if(bicomp == -1) bicomp = x;
			else bicomp = -2;
			return;
		}
		if(rep[x] > rep[y])
			swap(x, y);
		rep[x] += rep[y];
		rep[y] = x;
	}

	int max_deg = 0;
	void add_edge(int a, int b) {
		if(a == excluded || b == excluded)
			return;
		max_deg |= 3 <= ++deg[a];
		max_deg |= 3 <= ++deg[b];
		join(a, b);
	}

	Graph(int n = 0, int e = -1) : rep(n, -1), deg(n), excluded(e) {}
};

int n;
vector<pair<int, int>> edges;
Graph graph;
vector<Graph> without;

void Init(int N) {
	n = N;
	graph = Graph(n);
}

void Link(int A, int B) {
	edges.emplace_back(A, B);
	if(!graph.max_deg) {
		graph.add_edge(A, B);
		if(graph.max_deg) {
			if(graph.deg[A] != 3)
				swap(A, B);

			vector<int> crit = {A};
			for(auto &[u, v] : edges) {
				if(u == A) crit.emplace_back(v);
				if(v == A) crit.emplace_back(u);
			}

			for(int x : crit) {
				without.emplace_back(n, x);
				for(auto &[u, v] : edges)
					without.back().add_edge(v, u);		
			}
		}
	}
	else {
		for(auto &g : without)
			g.add_edge(A, B);
	}
}

int CountCritical() {
	if(!graph.max_deg) {
		if(graph.bicomp == -1) return n;
		if(graph.bicomp == -2) return 0;
		return graph.get_cycle();
	}
	else {
		int ret = 0;
		for(auto &g : without) {
			if(g.bicomp == -1 && !g.max_deg)
				ret++;
		}
		return ret;
	}
}

• Subtask 1: 20 / 20
• Subtask 2: 17 / 17
• Subtask 3: 18 / 18
• Subtask 4: 14 / 14
• Subtask 5: 31 / 31