05-树8 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.
题解:
#include <set>
#include <cmath>
#include <queue>
#include <stack>
#include <vector>
#include <string>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <functional>
#define mod 1000000007
const int INF = 0x7f7f7f7f;
typedef long long ll;
const int maxn = 10050;
using namespace std;
int vec[maxn] = {0};
int t;
int Find(int x)
{
int i;
if(vec[x] < 0)
return x;
for(i = vec[x]; vec[i]>=0; i = vec[i]);
return i;
}
void Union( int x, int y)
{
int root1, root2;
root1 = Find(x);
root2 = Find(y);
if(root1!=root2)
{
if(vec[root1]<vec[root2])
{
vec[root1] += vec[root2];
vec[root2] = root1;
t--;
}
else
{
vec[root2] += vec[root1];
vec[root1] = root2;
t--;
}
}
}
int main()
{
scanf("%d", &t);
getchar();
for(int i = 1; i <= t; i++)
{
vec[i] = -1;
}
while(1)
{
char temp;
scanf("%c", &temp);
if(temp == 'C')
{
int m, n;
scanf("%d%d", &m, &n);
getchar();
if(Find(m)==Find(n))
{
printf("yes\n");
}
else
{
printf("no\n");
//Union(m, n);
}
}
else
{
if(temp == 'I')
{
int m, n;
scanf("%d%d", &m, &n);
getchar();
Union(m,n);
}
else
{
if(t>1)
{
printf("There are %d components.\n", t);
break;
}
else
{
printf("The network is connected.\n");
break;
}
}
}
}
return 0;
}