Submission #733979

#	Time	Username	Problem	Language	Result	Execution time	Memory
733979		ismayil	Connecting Supertrees (IOI20_supertrees)	C++17	100 / 100	252 ms	23816 KiB

supertrees

#include "supertrees.h"
#include <bits/stdc++.h>
using namespace std;
const int MAX = 1e3 + 3;

struct DSU{
	int par[MAX];
	int find(int u){
		if(par[u] < 0) return u;
		return par[u] = find(par[u]);
	}
	bool unite(int u, int v){
		u = find(u), v = find(v);
		if(u == v) return false;
		if(par[u] > par[v]) swap(u, v);
		par[u] += par[v];
		par[v] = u;
		return true;
	}
	DSU(){
		memset(par, -1, sizeof(par));
	}
};
int construct(vector<vector<int>> p) 
{
	for(auto i : p) for(auto j : i) if(j == 3) return 0;
	DSU dsu1, dsu2;
	int n = p.size();
	vector<vector<int>> answer(n, vector<int>(n, 0));
	int mark[n] = {0};
	for (int i = 0; i < n; i++){
		for(int j = 0; j < n; j++){
			if(p[i][j] == 0 && dsu1.find(i) == dsu1.find(j)) return 0;
			if(p[i][j] != 1) continue;
			if(dsu1.unite(i, j)){
				answer[i][j] = answer[j][i] = 1;
			}
		}
	}
	for (int i = 0; i < n; i++){
		for(int j = 0; j < n; j++){
			if(p[dsu1.find(i)][dsu1.find(j)] == 2){
				dsu2.unite(dsu1.find(i), dsu1.find(j));
			} 
		}
	}
	for (int i = 0; i < n; i++){
		for(int j = 0; j < n; j++){
			if(dsu2.find(dsu1.find(i)) == dsu2.find(dsu1.find(j)) && p[dsu1.find(i)][dsu1.find(j)] == 0) return 0;
		}
	}
	vector<int> comp[n];
	for(int i = 0; i < n; i++){
		if(mark[dsu1.find(i)]) continue;
		mark[dsu1.find(i)] = 1;
		comp[dsu2.find(dsu1.find(i))].push_back(dsu1.find(i));
	}
	for(auto &v : comp){
		if(v.size() == 2) return 0;
		if(v.size() < 2) continue;
		for(int j = 0; j < v.size() - 1; j++) answer[v[j]][v[j + 1]] = answer[v[j + 1]][v[j]] = 1;
		answer[v[v.size() - 1]][v[0]] = answer[v[0]][v[v.size() - 1]] = 1;
	}
	build(answer);
	return 1;
}

Compilation message (stderr)

supertrees.cpp: In function 'int construct(std::vector<std::vector<int> >)':
supertrees.cpp:61:20: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   61 |   for(int j = 0; j < v.size() - 1; j++) answer[v[j]][v[j + 1]] = answer[v[j + 1]][v[j]] = 1;
      |                  ~~^~~~~~~~~~~~~~

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