Submission #559711

#	Time	Username	Problem	Language	Result	Execution time	Memory
559711		AlperenT	Connecting Supertrees (IOI20_supertrees)	C++17	0 / 100	1 ms	356 KiB

supertrees

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

using namespace std;

const int N = 1000 + 5;

struct DSU{
	int par[N], type[N];
	set<int> nodes[N];

	void reset(int n){
		for(int i = 0; i < n; i++) par[i] = i, type[i] = 0, nodes[i].insert(i);
	}

	int setfind(int a){
		if(par[a] == a) return a;
		else return par[a] = setfind(par[a]);
	}

	void setunion(int a, int b){
		a = setfind(a), b = setfind(b);

		if(a != b){
			if(nodes[b].size() > nodes[a].size()) swap(a, b);
			par[b] = par[a];
			type[b] = -1;
			for(auto x : nodes[b]) nodes[a].insert(x);
			nodes[b].clear();
		}
	}
};

DSU dsu;

int construct(vector<vector<int>> graph) {
	int n = graph.size();

	vector ans(n, vector(n, 0));

	dsu.reset(n);

	// finding 2 cycles

	set<int> curnodes;

	curnodes.clear();

	for(int i = 0; i < n; i++) curnodes.insert(i);

	for(int v = 0; v < n; v++){
		if(curnodes.count(v) && dsu.type[dsu.setfind(v)] == 0){
			curnodes.erase(v);

			for(auto u : curnodes){
				if(graph[v][u] == 2){
					bool flag = true;

					for(auto w : dsu.nodes[dsu.setfind(v)]){
						if(graph[u][w] != 2) flag = false;
					}

					if(flag){
						dsu.type[dsu.setfind(v)] = dsu.type[dsu.setfind(u)] = 2;
						dsu.setunion(v, u);
					}
				}
			}

			for(auto u : dsu.nodes[dsu.setfind(v)]) curnodes.erase(u);
		}
		else curnodes.erase(v);
	}

	for(int i = 0; i < n; i++){
		if(dsu.type[i] == 2){
			if(dsu.nodes[i].size() <= 1) return 0;

			vector<int> tmp;
			for(auto v : dsu.nodes[i]) tmp.push_back(v);

			for(int i = 0; i + 1 < tmp.size(); i++) ans[tmp[i]][tmp[i + 1]] = ans[tmp[i + 1]][tmp[i]] = 1;
			ans[tmp.back()][tmp.front()] = ans[tmp.front()][tmp.back()] = 1;
		}
	}

	for(int v = 0; v < n; v++){
		for(int u = 0; u < n; u++){
			if(dsu.setfind(v) != dsu.setfind(u) && graph[v][u] != 0) return 0;
		}
	}

	build(ans);
	return 1;
}

Compilation message (stderr)

supertrees.cpp: In function 'int construct(std::vector<std::vector<int> >)':
supertrees.cpp:82:25: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   82 |    for(int i = 0; i + 1 < tmp.size(); i++) ans[tmp[i]][tmp[i + 1]] = ans[tmp[i + 1]][tmp[i]] = 1;
      |                   ~~~~~~^~~~~~~~~~~~

• Subtask 1: 0 / 11
• Subtask 2: 0 / 10
• Subtask 3: 0 / 19
• Subtask 4: 0 / 35
• Subtask 5: 0 / 21
• Subtask 6: 0 / 4