Submission #1049844

#	Time	Username	Problem	Language	Result	Execution time	Memory
1049844		aykhn	Connecting Supertrees (IOI20_supertrees)	C++17	46 / 100	109 ms	24280 KiB

supertrees

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

using namespace std;

struct DSU
{
	vector<int> e;
	void init(int n)
	{
		e.assign(n, -1);
	}
	int get(int x)
	{
		if (e[x] < 0) return x;
		return e[x] = get(e[x]);
	}
	int unite(int x, int y)
	{
		x = get(x), y = get(y);
		if (x == y) return 0;
		if (e[x] > e[y]) swap(x, y);
		e[x] += e[y];
		e[y] = x;
		return 1;
	}
};

int construct(std::vector<std::vector<int>> p) {
	int n = p.size();
	vector<vector<int>> ans(n, vector<int> (n, 0));
	DSU dsu;
	dsu.init(n);
	for (int i = 0; i < n; i++)
	{
		for (int j = 0; j < n; j++)
		{
			if (p[i][j] == 3) return 0;
			if (p[i][j] == 1 && dsu.unite(i, j)) ans[i][j] = ans[j][i] = 1;
		}
	}
	vector<int> comp[n];
	for (int i = 0; i < n; i++) comp[dsu.get(i)].push_back(i);
	DSU d1;
	d1.init(n);
	for (int i = 0; i < n; i++)
	{
		if (i != dsu.get(i)) continue;
		for (int &j : comp[i])
		{
			for (int k = 0; k < n; k++)
			{
				if ((p[j][k] == 2) != (p[i][k] == 2)) return 0;
			}
		}
		for (int j = 0; j < n; j++)
		{
			if (p[i][j] == 2) d1.unite(i, dsu.get(j));
		}
	}
	vector<int> con[n];
	for (int i = 0; i < n; i++) con[d1.get(i)].push_back(i);
	for (int i = 0; i < n; i++)
	{
		if (con[i].size() <= 1) continue;
		if (con[i].size() == 2) return 0;
		int prev = con[i].back();
		for (int &j : con[i]) 
		{
			ans[prev][j] = ans[j][prev] = 1;
			prev = j;
		}
	}
	build(ans);
	return 1;
}

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