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>
using namespace std;
#define MAXSize 10001
typedef int ElementType;
typedef int SetName;
typedef ElementType SetType[MAXSize];
void Initialization(SetType s, int n) {
for (int i = 0; i < n; i++)
{
s[i] = -1;
}
}
SetName Find(SetType s, ElementType x) {
if (s[x] < 0) return x;
else return s[x] = Find(s, s[x]);
}
void Union(SetType s, int root1, int root2) {
if (s[root1] < s[root2])
s[root2] = root1;
else
{
if (s[root1] == s[root2]) s[root2]--;
s[root1] = root2;
}
}
void INput_connection(SetType s) {
ElementType a, b;
SetName root1, root2;
cin >> a >> b;
root1 = Find(s, a-1);
root2 = Find(s, b-1);
if (root1!=root2)
{
Union(s, root1, root2);
}
}
void Check_connection(SetType s) {
ElementType a, b;
SetName root1, root2;
cin >> a >> b;
root1 = Find(s, a-1);
root2 = Find(s, b-1);
if (root1 == root2) cout << "yes" << endl;
else cout <<"no" << endl;
}
void Check_network(SetType s, int n) {
int i, num=0;
for ( i = 0; i < n; i++)
{
if (s[i] < 0) num++;
}
if (num == 1)
cout << "The network is connected." << endl;
else
cout << "There are" << ' ' << num << " components." << endl;
}
int main()
{
SetType s;
int n;
char in;
cin >> n;
Initialization(s, n);
do
{
cin >> in;
switch (in)
{
case'I': INput_connection(s); break;
case'C': Check_connection(s); break;
case'S': Check_network(s, n); break;
}
} while (in!='S');
return 0;
}