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≤N≤104), 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 c1
and c2
; or
S
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 k
is the number of connected components in this network.
Sample Input 1:
5
C 3 2
I 3 2
C 1 5
I 4 5
I 2 4
C 3 5
S
Sample Output 1:
no
no
yes
There are 2 components.
Sample Input 2:
5
C 3 2
I 3 2
C 1 5
I 4 5
I 2 4
C 3 5
I 1 3
C 1 5
S
Sample Output 2:
no
no
yes
yes
The network is connected.
#include <iostream>
#include <vector>
using namespace std;
#define Max_Node 10001
typedef struct
{
int parent;
}Node;
int Find_Set(vector<Node> &set,int value)//寻找当前value所在的并查集的根结点
{
while (set[value].parent>0)
{
value=set[value].parent;
}
return value;
}
void Union_Set(vector<Node> &set,int value1,int value2)//合并两个结点的并查集
{
int root1=Find_Set(set, value1);
int root2=Find_Set(set, value2);
if (set[root1].parent<set[root2].parent)//以root1为根的并查集的结点个数更多,将并查集结点个数少的合并到结点个数多的并查集
{
set[root2].parent=root1;
set[root1].parent--;
}else
{
set[root1].parent=root2;
set[root2].parent--;
}
}
bool Check_Set(vector<Node> &set,int value1,int value2)//查询两结点是否在同一个并查集
{
int root1=Find_Set(set, value1);
int root2=Find_Set(set, value2);
if (root1==root2)
{
return true;
}else
{
return false;
}
}
int Count_Set(vector<Node> &set)//查询当前并查集的个数
{
int count=0;
for (int i=1; i<=set.size(); ++i)
{
if (set[i].parent<0)//parent小于0则该结点为一个并查集的根
{
count++;
}
}
return count;
}
int main()
{
int N=0;
cin>>N;
vector<Node> Set(N+1);
for (int i=1; i<=N; ++i)
{
Set[i].parent=-1;
}
char str;
int value1=0,value2=0;
while (1)
{
cin>>str;
if (str=='S')
{
break;
}else if(str=='I')
{
cin>>value1>>value2;
Union_Set(Set, value1, value2);
}else
{
cin>>value1>>value2;
if (Check_Set(Set, value1, value2))
{
cout<<"yes\n";
}else
{
cout<<"no\n";
}
}
}
int count=Count_Set(Set);
if (count>1)
{
cout<<"There "<<"are "<<count<<" components.";
}else
{
cout<<"The network is connected.";
}
return 0;
}