Submission #301624

#TimeUsernameProblemLanguageResultExecution timeMemory
301624jwvg0425Connecting Supertrees (IOI20_supertrees)C++17
100 / 100
267 ms22396 KiB
#include "supertrees.h"
#include <vector>
#include <set>

using namespace std;

int cpar[1005];
int tpar[1005];
set<int> cv[1005];

int tfind(int x)
{
	if (tpar[x] == x)
		return x;

	return tpar[x] = tfind(tpar[x]);
}

void tmerge(int x, int y)
{
	x = tfind(x);
	y = tfind(y);

	tpar[x] = y;
}

int cfind(int x)
{
	if (cpar[x] == x)
		return x;

	return cpar[x] = cfind(cpar[x]);
}

void cmerge(int x, int y)
{
	x = cfind(x);
	y = cfind(y);

	cpar[x] = y;
}

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

	for (int i = 0; i < n; i++)
		cpar[i] = tpar[i] = i;

	vector<vector<int>> answer;
	for (int i = 0; i < n; i++)
	{
		vector<int> row;
		row.resize(n);
		answer.push_back(row);
	}

	for (int i = 0; i < n; i++)
	{
		for (int j = i + 1; j < n; j++)
		{
			if (p[i][j] == 0)
				continue;

			if (p[i][j] == 1)
			{
				if (tfind(i) == tfind(j))
					continue;

				tmerge(i, j);
				answer[i][j] = answer[j][i] = 1;
				continue;
			}

			if (p[i][j] >= 2)
				cmerge(i, j);
		}
	}

	for (int i = 0; i < n; i++)
	{
		for (int j = i + 1; j < n; j++)
		{
			if (p[i][j] == 0)
			{
				if (cfind(i) == cfind(j) || tfind(i) == tfind(j))
					return 0;
			}

			if (p[i][j] == 1)
			{
				if (tfind(i) != tfind(j))
					return 0;
			}

			if (p[i][j] >= 2)
			{
				if (cfind(i) != cfind(j) || tfind(i) == tfind(j))
					return 0;

				cv[cfind(i)].insert(p[i][j]);
			}
		}
	}

	for (int i = 0; i < n; i++)
	{
		if (cfind(i) != i)
			continue;

		set<int> ts;

		for (int j = 0; j < n; j++)
		{
			if (cfind(j) != i)
				continue;

			ts.insert(tfind(j));
		}

		vector<int> tv;
		for (auto ti : ts)
			tv.push_back(ti);

		int k = tv.size();

		if (k <= 1)
			continue;

		if (cv[i].size() >= 2 || *cv[i].begin() == 3)
			return 0;

		if (k <= 2)
			return 0;

		for (int x = 0; x < k; x++)
		{
			int nx = (x + 1) % k;
			answer[tv[x]][tv[nx]] = answer[tv[nx]][tv[x]] = 1;
		}
	}

	build(answer);
	return 1;
}
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