File Transfer
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.
本题还可以做路径压缩等优化,本人并没有,请见陈越老师详解
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 #include<iostream> 2 #include<vector> 3 using namespace std; 4 struct node{ 5 int data; 6 int parent=-1; 7 }; 8 int size; 9 int Find(vector<node> &set,int data){ 10 int q=data-1; 11 while(set[q].parent>0) 12 q=set[q].parent; 13 return q; 14 } 15 void connect(vector<node> &set,int i,int j){ 16 int m=Find(set,i); 17 int n=Find(set,j); 18 if(set[m].parent<set[n].parent){ 19 set[m].parent+=set[n].parent; set[n].parent=m; 20 } 21 else {set[n].parent+=set[m].parent; set[m].parent=n;} 22 } 23 void query(vector<node> &set,int i,int j){ 24 int m=Find(set,i); int n=Find(set,j); 25 if(m==n) cout<<"yes"<<endl; 26 else cout<<"no"<<endl; 27 } 28 int main(){ 29 int i=1,j,num; cin>>size; 30 num=size; 31 vector<node> set(size); 32 for(int p=0;p<size;p++) 33 set[p].data=p+1; 34 string str; cin>>str; 35 while(str!="S"){ 36 if(str=="C"){ 37 cin>>i>>j; 38 query(set,i,j); 39 } 40 else{ 41 cin>>i>>j; 42 connect(set,i,j); 43 num--; 44 } 45 cin>>str; 46 } 47 if(num==1) 48 cout<<"The network is connected."<<endl; 49 else 50 cout<<"There are "<<num<<" components."<<endl; 51 return 0; 52 }