Submission #777810

#	Time	Username	Problem	Language	Result	Execution time	Memory
777810		Minindu206	Connecting Supertrees (IOI20_supertrees)	C++14	100 / 100	198 ms	24248 KiB

supertrees

#include "supertrees.h"
#include <vector>
#include <bits/stdc++.h>
using namespace std;
struct DSU
{
	/* data */
	int n;
	vector<int> par, sz;
	void init(int _n)
	{
		n = _n;
		par.resize(n + 1, -1);
		sz.resize(n + 1, 0);
	}
	int finds(int a)
	{
		if (par[a] == -1)
			return a;
		return par[a] = finds(par[a]);
	}
	void unites(int a, int b)
	{
		int x = finds(a);
		int y = finds(b);
		if (x != y)
		{
			if (sz[x] < sz[y])
				swap(x, y);
			par[y] = x;
			sz[x] += sz[y];
		}
	}
};
int construct(std::vector<std::vector<int>> p)
{
	int n = p.size();
	DSU d;
	d.init(n);
	for (int i = 0; i < n; i++)
	{
		for (int j = 0; j < n; j++)
		{
			if (i == j)
				continue;
			if (p[i][j] == 3)
				return 0;
			if (p[i][j])
			{
				d.unites(i, j);
			}
		}
	}
	map<int, vector<int>> mp;
	for (int i = 0; i < n; i++)
	{
		mp[d.finds(i)].push_back(i);
		for (int j = 0; j < n; j++)
		{
			if (i == j)
				continue;
			if (p[i][j] == 0)
				if (d.finds(i) == d.finds(j))
					return 0;
		}
	}
	vector<vector<int>> ans(n, vector<int>(n, 0));
	for (auto a : mp)
	{
		if (a.second.size() == 1)
			continue;
		int csz = a.second.size();
		vector<int> vis(n, 0), cyc;
		for(auto b:a.second)
		{
			if(vis[b])
				continue;
			cyc.push_back(b);
			vis[b] = 1;
			for(auto c:a.second)
			{
				if(vis[c] == 1)
					continue;
				if(p[b][c] == 1)
				{
					vis[c] = 1;
					ans[b][c] = 1;
					ans[c][b] = 1;
				}
			}
		}
		if(cyc.size() == 2)
			return 0;
		int st = -1;
		for(auto b:cyc)
		{
			if(st == -1)
				st = b;
			else
			{
				ans[st][b] = 1;
				ans[b][st] = 1;
				st = b;
			}
		}
		if(cyc.size() > 2)
		{
			ans[st][cyc[0]] = 1;
			ans[cyc[0]][st] = 1;
		}
	}
	build(ans);
	return 1;
}

Compilation message (stderr)

supertrees.cpp: In function 'int construct(std::vector<std::vector<int> >)':
supertrees.cpp:72:7: warning: unused variable 'csz' [-Wunused-variable]
   72 |   int csz = a.second.size();
      |       ^~~

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