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("\n  %d %d\n", a, b);

31                 total++;

32             }

33             else

34             mercy(a, b);

35         }

36         printf("%d\n", total);

37     }

38 }