杭电2120--Ice_cream's world I（并查集）

Ice_cream's world I

Time Limit: 3000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 758 Accepted Submission(s): 442

Problem Description

ice_cream's world is a rich country, it has many fertile lands. Today, the queen of ice_cream wants award land to diligent ACMers. So there are some watchtowers are set up, and wall between watchtowers be build, in order to partition the ice_cream’s world. But how many ACMers at most can be awarded by the queen is a big problem. One wall-surrounded land must be given to only one ACMer and no walls are crossed, if you can help the queen solve this problem, you will be get a land.

Input

In the case, first two integers N, M (N<=1000, M<=10000) is represent the number of watchtower and the number of wall. The watchtower numbered from 0 to N-1. Next following M lines, every line contain two integers A, B mean between A and B has a wall(A and B are distinct). Terminate by end of file.

Output

Output the maximum number of ACMers who will be awarded.
One answer one line.

Sample Input

8 10 

0 1

1 2

1 3

2 4

3 4

0 5

5 6

6 7

3 6

4 7

Sample Output

3

Author

Wiskey

Source

HDU 2007-10 Programming Contest_WarmUp

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//计算成环个数；

 1 #include <stdio.h>
 2 int father[1010];
 3 int find(int a)
 4 {
 5     while(a != father[a])
 6     a = father[a];
 7     return a;
 8 }
 9 void mercy(int a, int b)
10 {
11     int q = find(a);
12     int p = find(b);
13     if(q != p)
14     father[q] = p;
15 }
16 int main()
17 {
18     int i, n, m;
19     while(~scanf("%d %d", &n, &m))
20     {
21         int total = 0;
22         for(i=0; i<n; i++)
23         father[i] = i;
24         for(i=0; i<m; i++)
25         {
26             int a, b;
27             scanf("%d %d", &a, &b);
28             if(find(a) == find(b))
29             {
30                 //printf("
  %d %d
", a, b);
31                 total++;
32             }
33             else
34             mercy(a, b);
35         }
36         printf("%d
", total);
37     }
38 }