Submission #568467

#	Time	Username	Problem	Language	Result	Execution time	Memory
568467		Jomnoi	Connecting Supertrees (IOI20_supertrees)	C++17	96 / 100	847 ms	26424 KiB

supertrees

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

const int MAX_N = 1e3 + 5;

int n;
vector <int> graph[MAX_N];
bool visited[MAX_N];
vector <vector <int>> answer;
int cmp[MAX_N];
int parent[MAX_N];
vector <int> vertex[MAX_N];

int root(int u) {
	if(u == parent[u]) {
		return u;
	}
	return parent[u] = root(parent[u]);
}

void dfs(int u) {
	visited[u] = true;
	for(auto v : graph[u]) {
		if(visited[v] == false) {
			cmp[v] = cmp[u];
			answer[u][v] = answer[v][u] = 1;
			dfs(v);
		}
	}
}

int solve(vector <int> nodes, vector <vector <int>> p) {
	bool two = false, three = false;
	
	for(auto u : nodes) {
		for(auto v : nodes) {
			if(u < v and p[u][v] == 1) {
				graph[u].push_back(v);
				graph[v].push_back(u);
			}
		}
	}

	for(auto u : nodes) {
		if(visited[u] == false) {
			visited[u] = true;
			cmp[u] = u;
			dfs(u);
		}
	}

	for(auto u : nodes) {
		parent[u] = u;
	}
	for(auto u : nodes) {
		for(auto v : nodes) {
			if(u < v and p[u][v] == 2 or p[u][v] == 3) {
				if(p[u][v] == 2) {
					two = true;
				}
				else if(p[u][v] == 3) {
					three = true;
				}

				parent[root(cmp[v])] = root(cmp[u]);
			}
		}
	}

	if(two == true and three == true) {
		return 0;
	}
	if(two == true or three == true) {
		vector <int> cycle;
		for(auto u : nodes) {
			if(cmp[u] == u) {
				cycle.push_back(u);
			}
		}
		if(two == true and cycle.size() <= 2) {
			return 0;
		}
		if(three == true and cycle.size() <= 3) {
			return 0;
		}

		int pr = cycle.back();
		for(auto v : cycle) {
			answer[v][pr] = answer[pr][v] = 1;
			pr = v;
		}

		if(three == true) {
			answer[cycle[0]][cycle[2]] = answer[cycle[2]][cycle[0]] = 1;
		}
	}
	return 1;
}

int construct(vector <vector <int>> p) {
	n = p.size();
	fill(cmp, cmp + n, -1);
	answer.resize(n, vector <int> (n, 0));

	iota(parent, parent + n, 0);
	for(int i = 0; i < n; i++) {
		for(int j = i + 1; j < n; j++) {
			if(p[i][j] != 0) {
				parent[root(j)] = root(i);
			}
		}
	}
	for(int i = 0; i < n; i++) {
		for(int j = i + 1; j < n; j++) {
			if(p[i][j] == 0 and root(i) == root(j)) {
				return 0;
			}
		}
	}

	vector <int> components;
	for(int i = 0; i < n; i++) {
		vertex[root(i)].push_back(i);
		if(i == root(i)) {
			components.push_back(i);
		}
	}
	for(auto c : components) {
		if(solve(vertex[c], p) == 0) {
			return 0;
		}
	}

	build(answer);
	return 1;
}

Compilation message (stderr)

supertrees.cpp: In function 'int solve(std::vector<int>, std::vector<std::vector<int> >)':
supertrees.cpp:58:13: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   58 |    if(u < v and p[u][v] == 2 or p[u][v] == 3) {
      |       ~~~~~~^~~~~~~~~~~~~~~~

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