05-树8 File Transfer (25分)

最新推荐文章于 2019-05-18 22:53:44 发布

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05-树8 File Transfer (25分)

We have a network of computers and a list of bi-directional connections. Each of these connections allows a file transfer from one computer to another. Is it possible to send a file from any computer on the network to any other?

Input Specification:

Each input file contains one test case. For each test case, the first line contains $N$ ( $2\le N\le 10^4$ ), the total number of computers in a network. Each computer in the network is then represented by a positive integer between 1 and $N$ . Then in the following lines, the input is given in the format:

I c1 c2

where I stands for inputting a connection between c1 and c2; or

C c1 c2

where C stands for checking if it is possible to transfer files between c1and c2; or

where S stands for stopping this case.

Output Specification:

For each C case, print in one line the word "yes" or "no" if it is possible or impossible to transfer files between c1 and c2, respectively. At the end of each case, print in one line "The network is connected." if there is a path between any pair of computers; or "There are k components." where kis the number of connected components in this network.

Sample Input 1:

Sample Output 1:

no
no
yes
There are 2 components.

Sample Input 2:

Sample Output 2:

no
no
yes
yes
The network is connected.

真是难受，一个简单的符号，弄了很久，好在最后还是自己检查出来了。并查集的基本操作，用了按树的高度来union。也没有用路径压缩。感觉自己真是菜。。

#include<iostream>
#define maxsize 10005
using namespace std;
typedef int SetType[maxsize];
void Initialize(SetType S,int n)
{
	for(int i=0;i<n;i++)
	{
		S[i]=-1;
	}
}
int Find(SetType S,int x)
{
	while(S[x]>=0)
	{
		x=S[x];
	}
	return x;
}
void Union(SetType S,int root1,int root2)
{
	if(S[root2]<S[root1])
	{
		S[root1]=root2;
	}
	else
		{
		if(S[root1]==S[root2])
			S[root1]--;
			S[root2]=root1;
		}
}
void Input(SetType S)
{
	int a,b;
	cin>>a>>b;
	int root1=Find(S,a-1);
	int root2=Find(S,b-1);
	if(root1!=root2)
	{
		Union(S,root1,root2);
	}
}
void Check(SetType S)
{
	int a,b;
	cin>>a>>b;
	int root1=Find(S,a-1);
	int root2=Find(S,b-1);
	if(root1==root2)
	{
		cout<<"yes"<<endl;
	}
	else
	{
		cout<<"no"<<endl;
	}
}
void Recheck(SetType S,int n)
{
	int cnt=0;
	for(int i=0;i<n;i++)
	{
		if(S[i]<0)
			cnt++;
	}
	if(cnt==1)
	{
		cout<<"The network is connected."<<endl;
	}
	else
	{
		cout<<"There are "<<cnt<<" components."<<endl;
	}
}
int main()
{
	int n;
	SetType S;
	char in;
	cin>>n;
	Initialize(S,n);
	do
	{
//		while((c=getchar())!='\n');
		cin>>in;
		switch(in)
		{
			case 'I':Input(S); break;
			case 'C':Check(S); break;
			case 'S':Recheck(S,n); break;
		}
	}
	while(in!='S');
	return 0;
}