Submission #300294

#	Time	Username	Problem	Language	Result	Execution time	Memory
300294		jtnydv25	Connecting Supertrees (IOI20_supertrees)	C++17	56 / 100	338 ms	24868 KiB

supertrees

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

#define all(c) ((c).begin()), ((c).end())

struct dsu{
	vector<vector<int>> components;
	int n;
	vector<int> par;
	dsu(int n) : n(n), par(n){
		iota(all(par), 0);
		components.resize(n);
		for(int i = 0; i < n; i++) components[i] = {i};
	}
	int root(int x){
		return x == par[x] ? x : (par[x] = root(par[x]));
	}
	void merge(int x, int y){
		x = root(x); y = root(y);
		if(x == y) return;
		copy(all(components[x]), back_inserter(components[y]));
		components[x].clear();
		par[x] = y;
	}
};

int construct(vector<vector<int>> p) {
	int n = p.size();
	vector<vector<int>> adj(n, vector<int>(n, 0));
	function<void(int, int)> add_edge = [&](int x, int y){
		adj[x][y] = adj[y][x] = 1;
	};
	dsu D(n);
	for(int i = 0; i < n; i++){
		if(p[i][i] != 1) return 0;
		for(int j = i + 1; j < n; j++){
			if(p[i][j] != p[j][i]) return 0;
			if(p[i][j] > 0) D.merge(i, j);
		}
	}

	for(int i = 0; i < n; i++) if(D.par[i] == i){
		vector<int> v = D.components[i];
		for(int x : v) for(int y : v) if(p[x][y] == 0 || p[x][y] == 3) return 0;
		dsu D2(n);
		for(int x : v) for(int y : v) if(x != y && p[x][y] == 1) D2.merge(x, y);
		vector<int> cycle;
		for(int x : v) if(D2.par[x] == x){
			cycle.push_back(x);
			vector<int> U = D2.components[x];
			int lst = -1;
			for(int a : U){
				for(int b : U) if(p[a][b] != 1) return 0;
				if(lst != -1) add_edge(a, lst);
				lst = a;
			}
		}
		int m = cycle.size();
		if(m > 1)
		for(int k = 0; k < m; k++) add_edge(cycle[k], cycle[(k + 1) % m]);
	}
	build(adj);

	return 1;
}

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