Submission #508090

#	Time	Username	Problem	Language	Result	Execution time	Memory
508090		jamezzz	Connecting Supertrees (IOI20_supertrees)	C++17	100 / 100	261 ms	24180 KiB

supertrees

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

struct ufds{
	int par[1005],rnk[1005];
	void init(int n){
		for(int i=0;i<n;++i)par[i]=i,rnk[i]=0;
	}
	int fp(int i){return (par[i]==i)?i:par[i]=fp(par[i]);}
	void join(int x,int y){
		x=fp(x),y=fp(y);
		if(x==y)return;
		if(rnk[x]<rnk[y])par[x]=y;
		else par[y]=x;
		if(rnk[x]==rnk[y])++rnk[x];
	}
}u;

int construct(vector<vector<int>> p){
	int n=p.size();
	u.init(n);
	for(int i=0;i<n;++i){
		for(int j=0;j<n;++j){
			if(p[i][j]==3)return 0;
			if(p[i][j]!=0)u.join(i,j);
		}
	}
	vector<vector<int>> c1;
	c1.resize(n);
	for(int i=0;i<n;++i){
		c1[u.fp(i)].push_back(i);
		for(int j=0;j<n;++j){
			if(u.fp(i)==u.fp(j)&&p[i][j]==0){
				return 0;
			}
		}
	}

	u.init(n);
	for(int i=0;i<n;++i){
		for(int j=0;j<n;++j){
			if(p[i][j]==1)u.join(i,j);
		}
	}
	vector<vector<int>> c2,c3;
	c2.resize(n);
	c3.resize(n);
	for(int i=0;i<n;++i){
		c2[u.fp(i)].push_back(i);
		for(int j:c1[i]){//single cycle
			if(u.fp(j)==j)c3[i].push_back(j);
		}
	}
	
	for(int i=0;i<n;++i){
		for(int a:c1[i]){
			for(int b:c1[i]){
				if(u.fp(a)!=u.fp(b)&&p[a][b]!=2){
					return 0;
				}
				if(u.fp(a)==u.fp(b)&&p[a][b]!=1){
					return 0;
				}
			}
		}
	}
	
	vector<vector<int>> answer;
	answer.resize(n);
	for(int i=0;i<n;++i)answer[i].resize(n);
	for(int i=0;i<n;++i){
		for(int j:c2[i]){
			if(i!=j)answer[i][j]=answer[j][i]=1;
		}
	}
	for(int i=0;i<n;++i){
		if(c3[i].size()==2)return 0;
		if(c3[i].size()>=3){
			int m=c3[i].size();
			for(int j=0;j<m;++j){
				int a=c3[i][j],b=c3[i][(j+1)%m];
				if(a!=b)answer[a][b]=answer[b][a]=1;
			}
		}
	}
	build(answer);
	return 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