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), 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<cstdio> const int maxn = 1010; void Initialization( int n); void Input_connection(); int FindFather(int x); void Check_connection(); void Check_network(int n); int arr[maxn]; int main() { int n; char in; scanf("%d",&n); Initialization(n); do { getchar(); scanf("%c",&in); switch(in) { case 'I': { Input_connection(); break; } case 'C': { Check_connection(); break; } case 'S': { Check_network(n); break; } } }while (in != 'S'); return 0; } void Initialization( int n) { for (int i = 0; i <= n; i++) { arr[i] = i; } } void Input_connection() { int u,v; scanf("%d %d",&u,&v); int faA = FindFather(u); int faB = FindFather(v); if (faA != faB) { arr[faA] = faB; } } int FindFather(int x) { if (arr[x] == x) { return x; } else { return arr[x] = FindFather(arr[x]); } } void Check_connection() { int u,v; scanf("%d %d",&u,&v); int faA = FindFather(u); int faB = FindFather(v); if (faA != faB) { printf("no "); } else { printf("yes "); } } void Check_network(int n) { int cnt = 0; for (int i = 1; i <= n; i++) { if (arr[i] == i) { cnt++; } } if (1 == cnt) { printf("The network is connected."); } else { printf("There are %d components.",cnt); } }