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05-树8 File Transfer（25 分）

2017-10-28 20:33 525 查看 


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≤10​4​​),
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:
[code]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.


一定要做到的是归并树时要按照大小，而且最好要进行路径压缩。

#include <cstdio>
#include <cstring>
//#define LOCAL
#define MAXSIZE 10010
int father[MAXSIZE];

void init(int size) {
for(int i=0; i<size; ++i) {
father[i] = -1;
}
}

int Find(int x) {
if(father[x] < 0) return x;
else return father[x] = Find(father[x]);
}

bool isSameSet(int a, int b) {
int Fa = Find(a);
int Fb = Find(b);
return Fa==Fb;
}

void Union(int a, int b) {
int Fa = Find(a);
int Fb = Find(b);
if(Fa!=Fb) {
if(father[Fa] <= father[Fb]) {
father[Fa] += father[Fb];
father[Fb] = Fa;
}
else {
father[Fb] += father[Fa];
father[Fa] = Fb;
}
}

}

int main()
{
#ifdef LOCAL
freopen("test.txt", "r", stdin);
#endif
int num;
scanf("%d", &num);
init(num);
char ins;
do {
scanf("%c", &ins);
if(ins=='C') {
int a, b;
scanf("%d %d", &a, &b);
if(isSameSet(a, b))
printf("yes\n");
else printf("no\n");
}
else if(ins=='I') {
int a, b;
scanf("%d %d", &a, &b);
Union(a, b);
}
} while(ins != 'S');
int com = 0;
for(int i=0; i<num; ++i) {
if(father[i]<0) ++com;
}
if(com!=1)
printf("There are %d components.", com);
else
printf("The network is connected.");
return 0;
}


提交代码时，遇到了一些问题，即：我用fgets处理的数据，问题在于不一定原始数据每一行都有换行符。所以，AC代码里getchar更好。
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标签：  c++ c
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