Submission #578065

#	Time	Username	Problem	Language	Result	Execution time	Memory
578065		1ne	Connecting Supertrees (IOI20_supertrees)	C++14	100 / 100	204 ms	22108 KiB

supertrees

#include "supertrees.h"
#include <vector>
#include <cassert>
#include <cstdio>
#include <cstdlib>
#include <string>
#include <vector>
#include <bits/stdc++.h>
using namespace std;
struct DSU{
	vector<int>parent;
	vector<int>sz;
	vector<vector<int>>comp;
	void build(int n){
		parent.resize(n);
		sz.resize(n);
		comp.resize(n);
		for (int i = 0;i<n;++i){
			parent[i] = i;
			sz[i] = 1;
			comp[i].push_back(i);
		}
	}
	int findsets(int v){
		if (v == parent[v])return v;
		parent[v] = findsets(parent[v]);
		return parent[v];
	}
	bool unionset(int a,int b){
		int u = findsets(a);
		int v = findsets(b);
		if (u == v)return false;
		if (sz[u] < sz[v])swap(u,v);
		parent[v] = u;
		sz[u]+=sz[v];
		sz[v] = 0;
		while(!comp[v].empty()){
			comp[u].push_back(comp[v].back());
			comp[v].pop_back();
		}
		return true;
	}
};
int construct(std::vector<std::vector<int>> p) {
	int n = p.size();
	std::vector<std::vector<int>> answer(n,vector<int>(n,0));
	for (int i = 0;i<n;++i){
		for (int j = 0;j<n;++j){
			if (p[i][j] == 3)return 0;
		}
	}
	DSU st;
	st.build(n);
	for (int i = 0;i<n;++i){
		for (int j = i + 1;j<n;++j){
			int u = st.findsets(i);
			int v = st.findsets(j);
			if (p[i][j]==1 && st.unionset(i,j)){
				answer[u][v] = true;
				answer[v][u] = true;
			}
		}
	}
	vector<int>cyc(n,0);
	for (int i = 0;i<n;++i){
		vector<int>cycle;
		cycle.push_back(st.findsets(i));
		for (int j = 0;j<n;++j){
			if (p[i][j] == 2){
				if (st.findsets(i) == st.findsets(j))continue;
				cycle.push_back(st.findsets(j));
				st.unionset(i,j);
			}
		}
		if (cycle.size()==2)return 0;
		if (cycle.size()==1)continue;
		cyc[st.findsets(i)]++;
		for (int j = 0;j<cycle.size();++j){
			answer[cycle[j]][cycle[(j + 1)%(int)cycle.size()]] = true;
			answer[cycle[(j + 1)%(int)cycle.size()]][cycle[j]] = true;
		}
	}
	for (int i = 0;i<n;++i){
		for (int j = 0;j<n;++j){
			if (p[i][j] && st.findsets(i)!=st.findsets(j))return 0;
			if (!p[i][j] && st.findsets(i)==st.findsets(j))return 0;
		}
	}
	for (int i = 0;i<n;++i){
		if (cyc[st.findsets(i)] > 1)return 0;
	}
	build(answer);
	return 1;
}

Compilation message (stderr)

supertrees.cpp: In function 'int construct(std::vector<std::vector<int> >)':
supertrees.cpp:78:19: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   78 |   for (int j = 0;j<cycle.size();++j){
      |                  ~^~~~~~~~~~~~~

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