Submission #612899

#	Time	Username	Problem	Language	Result	Execution time	Memory
612899		jairRS	Connecting Supertrees (IOI20_supertrees)	C++17	0 / 100	1 ms	340 KiB

supertrees

#include "supertrees.h"
#include <bits/stdc++.h>
using namespace std;
using vi = vector<int>;
using vvi = vector<vi>;

struct DSU{
	vi p, s;
	DSU(int size){
		p = s = vi(size + 1, 1);
		for(int i = 0; i <= size; i++)
			p[i] = i;
	}

	int find(int x){
		if(p[x] == x)
			return x;
		return p[x] = find(p[x]);
	}

	void unite(int a, int b){
		a = find(a);
		b = find(b);
		if(a == b)
			return;
		if(s[a] > s[b])
			swap(a, b);
	
		s[b] += s[a];
		p[a] = b;
	}
};

int construct(vvi p) {
	int n = p.size();
	vvi answer = vvi(n, vi(n, 0));
	
	DSU dsu(n);
	for (int i = 0; i < n; i++)
		for (int j = i + 1; j < n; j++)
			if(p[i][j] == 2)
				dsu.unite(i, j);

	vvi group(n, vi());
	for (int i = 0; i < n; i++)
		group[dsu.find(i)].push_back(i);
	
	for (int i = 0; i < n; i++)
		for (int j = i + 1; j < n; j++)
			if(dsu.find(i) == dsu.find(j) && p[i][j] == 0)
				return 0;
	
	for(vi & g : group){
		if(g.size() == 1)
			continue;
		if(g.size() == 2)
			return 0;
		for (int i = 0; i + 1 < g.size(); i++)
		{
			answer[g[i]][g[i + 1]] = 1;
			answer[g[i + 1]][g[i]] = 1;
		}
		answer[g.back()][g[0]] = 1;
		answer[g[0]][g.back()] = 1;
	}

	build(answer);
	return 1;
}

Compilation message (stderr)

supertrees.cpp: In function 'int construct(vvi)':
supertrees.cpp:58:25: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   58 |   for (int i = 0; i + 1 < g.size(); i++)
      |                   ~~~~~~^~~~~~~~~~

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