Submission #1020505

#	Time	Username	Problem	Language	Result	Execution time	Memory
1020505		HappyCapybara	Connecting Supertrees (IOI20_supertrees)	C++17	100 / 100	231 ms	24420 KiB

supertrees

#include "supertrees.h"
#include<bits/stdc++.h>
using namespace std;

vector<int> par;

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

void merge(int a, int b){
	a = parent(a);
	b = parent(b);
	if (a == b) return;
	par[b] = a;
}

int construct(vector<vector<int>> p){
	int n = p.size();
	par.resize(n);
	for (int i=0; i<n; i++) par[i] = i;
	vector<vector<int>> answer(n, vector<int>(n, 0));
	for (int i=0; i<n; i++) {
		for (int j=0; j<n; j++){
			if (i == j) continue;
			if (p[i][j] == 0) continue;
			if (p[i][j] == 3) return 0;
			merge(i, j);
		}
	}
	for (int i=0; i<n; i++){
		for (int j=0; j<n; j++){
			if (p[i][j] == 0 && parent(i) == parent(j)) return 0;
		}
	}
	unordered_map<int,vector<int>> m;
	for (int i=0; i<n; i++) m[parent(i)].push_back(i);
	for (int i=0; i<n; i++) par[i] = i;
	for (int i=0; i<n; i++){
		if (m[i].size() == 0) continue;
		for (int x : m[i]){
			for (int y : m[i]){
				if (p[x][y] == 1) merge(x, y);
			}
		}
		for (int x : m[i]){
			for (int y : m[i]){
				if (p[x][y] == 2 && parent(x) == parent(y)) return 0;
			}
		}
		unordered_set<int> seen;
		vector<int> ofs;
		for (int x : m[i]){
			if (seen.find(parent(x)) == seen.end()){
				seen.insert(parent(x));
				ofs.push_back(parent(x));
			}
			if (parent(x) != x){
				answer[x][parent(x)] = 1;
				answer[parent(x)][x] = 1;
			}
		}
		if (ofs.size() == 1) continue;
		if (ofs.size() == 2) return 0;
		for (int j=0; j<ofs.size(); j++){
			answer[ofs[j]][ofs[(j+1)%ofs.size()]] = 1;
			answer[ofs[(j+1)%ofs.size()]][ofs[j]] = 1;
		}
	}
	build(answer);
	return 1;
}

Compilation message (stderr)

supertrees.cpp: In function 'int construct(std::vector<std::vector<int> >)':
supertrees.cpp:66:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   66 |   for (int j=0; j<ofs.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