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<cstdio> const int maxn = 10001; typedef int ElementType; typedef int setName; typedef int setType[maxn]; int Find(setType S,ElementType X){ if(S[X] < 0) return X; else return S[X] = Find(S,S[X]); } void Input_connection(setType S){ ElementType u,v; setName root1,root2; scanf("%d %d\n",&u,&v); root1 = Find(S,u-1); root2 = Find(S,v-1); if(root1 != root2) S[root1] = root2; } void Check_connection(setType S){ ElementType u,v; setName root1,root2; scanf("%d %d\n",&u,&v); root1 = Find(S,u-1); root2 = Find(S,v-1); if(root1 != root2) printf("no\n"); else printf("yes\n"); } void Check_network(setType S,int n){ int counter = 0; for(int i = 0; i < n; i++){ if(S[i] < 0) counter++; } if(counter == 1) printf("The network is connected.\n"); else printf("There are %d components.\n",counter); } void Initialization(setType S,int n){ for(int i = 0; i < n; i++){ S[i] = -1; } } //void check(setType S,int n){ // for(int i = 0 ; i < n; i++){ // printf("%d ",S[i]); // } //} int main(){ setType S; int n; char in; scanf("%d\n",&n); Initialization(S,n); do{ scanf("%c",&in); switch(in){ case 'I':Input_connection(S);break; case 'C':Check_connection(S);break; case 'S':Check_network(S,n);break; } //check(S,n); }while(in != 'S'); return 0; }