Submission #576820

#	Time	Username	Problem	Language	Result	Execution time	Memory
576820		1ne	Connecting Supertrees (IOI20_supertrees)	C++14	21 / 100	193 ms	22288 KiB

supertrees

#include "supertrees.h"
#include <vector>
#include <cassert>
#include <cstdio>
#include <cstdlib>
#include <string>
#include <vector>
#include <bits/stdc++.h>
using namespace std;
struct DSU{
	vector<int>parent;
	vector<int>sz;
	vector<vector<int>>comp;
	void build(int n){
		parent.resize(n);
		sz.resize(n);
		comp.resize(n);
		for (int i = 0;i<n;++i){
			parent[i] = i;
			sz[i] = 1;
			comp[i].push_back(i);
		}
	}
	int findsets(int v){
		if (v == parent[v])return v;
		parent[v] = findsets(parent[v]);
		return parent[v];
	}
	bool unionset(int a,int b,vector<vector<int>>&p,vector<vector<int>>&answer){
		int u = findsets(a);
		int v = findsets(b);
		if (u == v)return false;
		if (answer[u][v])return false;
		if (sz[u] < sz[v])swap(u,v);
		parent[v] = u;
		sz[u]+=sz[v];
		sz[v] = 0;
		answer[u][v] = true;
		answer[v][u] = true;
		while(!comp[v].empty()){
			comp[u].push_back(comp[v].back());
			comp[v].pop_back();
		}
		return true;
	};
};

int construct(std::vector<std::vector<int>> p) {
	int n = p.size();
	std::vector<std::vector<int>> answer(n,vector<int>(n,0));
	for (int i = 0;i<n;++i){
		for (int j = 0;j<n;++j){
			if (p[i][j] == 3)return 0;
		}
	}
	DSU st;
	st.build(n);
	for (int i = 0;i<n;++i){
		for (int j = i + 1;j<n;++j){
			if (p[i][j]){
				st.unionset(i,j,p,answer);
			}
		}
	}
	for (int i = 0;i<n;++i){
		for (int j = i + 1;j<n;++j){
			if (st.findsets(i) == st.findsets(j)){
				p[i][j]--;
				p[j][i]--;
			}
		}
	}
	for (int pp = 0;pp<n;++pp){
		for (int q = pp + 1;q<n;++q){
			int needone = 0;
			if (p[pp][q] > 0){
				int x = st.findsets(pp);
				assert(st.findsets(q) == x);
				set<pair<int,int>>brr;
				for (int i = 0;i<(int)st.comp[x].size();++i){
					for (int j = i + 1;j<(int)st.comp[x].size();++j){
						if (brr.find({st.comp[x][i],st.comp[x][j]})!=brr.end())continue;
						brr.insert({st.comp[x][i],st.comp[x][j]});
						brr.insert({st.comp[x][j],st.comp[x][i]});
						p[st.comp[x][i]][st.comp[x][j]]--;
						p[st.comp[x][j]][st.comp[x][i]]--;
						if (!needone && !answer[st.comp[x][i]][st.comp[x][j]]){
							needone = true;
							answer[st.comp[x][i]][st.comp[x][j]] = true;
							answer[st.comp[x][j]][st.comp[x][i]] = true;
						}
					}
				}
				if (!needone)return 0;
			}
		}
	}
	
	for (int i = 0;i<n;++i){
		for (int j = 0;j < n;++j){
			if (i == j)continue;
			if (p[i][j] != 0)return 0;
		}
	}
	build(answer);
	return 1;
}

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