Submission #567649

#	Time	Username	Problem	Language	Result	Execution time	Memory
567649		pere_gil	Connecting Supertrees (IOI20_supertrees)	C++17	100 / 100	227 ms	22524 KiB

supertrees

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

#define vvi vector<vector<int> >

struct union_find{
	vector<int> p;
	void init(int n){
		p.resize(n);
		iota(p.begin(),p.end(),0);
	}
	int find_set(int n){
		return (n==p[n]) ? n : p[n]=find_set(p[n]);
	}
	bool same_set(int a, int b){
		return find_set(a)==find_set(b);
	}
	void union_set(int a, int b){
		if(!same_set(a,b)) p[find_set(a)]=find_set(b);
	}
};

/*
void init(int n, vector<int> &p){
	for(int i=0;i<n;i++) p[i]=i;
}
int find_set(int n, vector<int> &p){
	return (n==p[n]) ? n : p[n]=find_set(p[n],p);
}
bool same_set(int a, int b, vector<int> &p){
	return find_set(a,p)==find_set(b,p);
}
void union_set(int a, int b, vector<int> &p){
	if(!same_set(a,b,p)) p[find_set(a,p)]=find_set(b,p);
}
*/

void join_1(vector<int> &g, vvi &res){
	for(int i=1;i<g.size();i++)
		res[g[i-1]][g[i]]=res[g[i]][g[i-1]]=1;
}
bool join_2(vector<int> &g, vvi &res){
	if(g.size()==1) return true;
	if(g.size()<3) return false;
	for(int i=0;i<g.size();i++){
		int j=(i+1)%g.size();
		res[g[i]][g[j]]=res[g[j]][g[i]]=1;
	}
	return true;
}

bool make_group(int n, vector<int> &g, vvi &v, vvi &res){
	//vector<int> p(n);
	//init(n,p);
	union_find p; p.init(n);

	unordered_set<int> mid;
	for(int i=0;i<g.size();i++){
		int aux=0;
		for(int j=0;j<g.size();j++)
			if(v[g[i]][g[j]]==1) p.union_set(g[i],g[j]);
			else aux++;
		if(aux==g.size()-1) mid.insert(g[i]);
	}
	vvi one(n);
	for(int i=0;i<g.size();i++){
		if(mid.find(g[i])==mid.end())
			one[p.find_set(g[i])].push_back(g[i]);
		if(g[i]==p.find_set(g[i])) mid.insert(g[i]);
	}
	vector<int> v_mid(mid.begin(),mid.end());

	for(int i=0;i<n;i++)
		if(one[i].size()) join_1(one[i],res);
	return join_2(v_mid,res);
}

int construct(vvi v){
	int n=v.size();

	//vector<int> p(n);
	//init(n,p);
	union_find p; p.init(n);
	for(int i=0;i<n;i++)
		for(int j=0;j<n;j++)
			if(v[i][j]) p.union_set(i,j);

    vvi g(n);
	for(int i=0;i<n;i++)
		g[p.find_set(i)].push_back(i);

	for(int i=0;i<n;i++)
		for(int j=0;j<n;j++)
			if((p.same_set(i,j) && v[i][j]==0) || v[i][j]==3) return 0;

	vvi res(n,vector<int> (n,0));
	for(int i=0;i<n;i++)
		if(g[i].size()>0)
			if(!make_group(n,g[i],v,res)) return 0;

	build(res);
	return 1;
}

Compilation message (stderr)

supertrees.cpp: In function 'void join_1(std::vector<int>&, std::vector<std::vector<int> >&)':
supertrees.cpp:40:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   40 |  for(int i=1;i<g.size();i++)
      |              ~^~~~~~~~~
supertrees.cpp: In function 'bool join_2(std::vector<int>&, std::vector<std::vector<int> >&)':
supertrees.cpp:46:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   46 |  for(int i=0;i<g.size();i++){
      |              ~^~~~~~~~~
supertrees.cpp: In function 'bool make_group(int, std::vector<int>&, std::vector<std::vector<int> >&, std::vector<std::vector<int> >&)':
supertrees.cpp:59:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   59 |  for(int i=0;i<g.size();i++){
      |              ~^~~~~~~~~
supertrees.cpp:61:16: 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<g.size();j++)
      |               ~^~~~~~~~~
supertrees.cpp:64:9: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   64 |   if(aux==g.size()-1) mid.insert(g[i]);
      |      ~~~^~~~~~~~~~~~
supertrees.cpp:67:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   67 |  for(int i=0;i<g.size();i++){
      |              ~^~~~~~~~~

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