05 - 树 8 File Transfer (25 分)

<pre><small><small>
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?
</small></small></pre>
<pre><small><small>
Input Specification:
Each input file contains one test case.
For each test case, the first line contains N (2<=N<=10000),
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.
</small></small></pre>
<pre><small><small>
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 5S
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.
</small></small></pre>
<pre><small><small>
#include <stdio.h>
#define ElementType int
typedef struct{
ElementType Data;
int Parent;
}SetType;
int Find( SetType S[], ElementType X);
void Union(SetType S[], ElementType X1, ElementType X2);
</small></small></pre>
<pre><small><small>
int Find( SetType S[], ElementType X){
// int i;
// for(i=0; i<N && S[i].Data!=X; ++i);
int i = X-1;
for( ; S[i].Parent>=0; i=S[i].Parent);
return i;
}
</small></small></pre>
<pre><small><small>
void Union(SetType S[], ElementType X1, ElementType X2){
int Root1, Root2;
Root1 = Find(S, X1);
Root2 = Find(S, X2);
// S[Root2].Parent = Root1;
if(S[Root1].Parent< S[Root2].Parent){
S[Root1].Parent += S[Root2].Parent;
S[Root2].Parent = Root1;
} else{
S[Root2].Parent += S[Root1].Parent;
S[Root1].Parent = Root2;
}
}
</small></small></pre>