HDU1213+并查集

简单的并查集

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 1 /*

 2 并查集

 3 */

 4 #include<stdio.h>

 5 #include<string.h>

 6 #include<stdlib.h>

 7 #include<algorithm>

 8 #include<iostream>

 9 #include<queue>

10 //#include<map>

11 #include<math.h>

12 using namespace std;

13 typedef long long ll;

14 //typedef __int64 int64;

15 const int maxn = 1005;

16 const int inf = 0x7fffffff;

17 const double pi=acos(-1.0);

18 const double eps = 1e-8;

19 int fa[ maxn ];

20 void init( int n ){

21     for( int i=1;i<=n;i++ )

22         fa[ i ]=i;

23 }

24 int find( int x ){

25     if( fa[x]==x ) return x;

26     fa[x]=find( fa[x] );

27     return fa[x];

28 }

29 void union_xy( int x,int y ){

30     int fa_x,fa_y;

31     fa_x = find( x );

32     fa_y = find( y );

33     if( fa_x>fa_y )

34         fa[ fa_y ]=fa_x;

35     else 

36         fa[ fa_x ]=fa_y;

37 }        

38 int main(){

39     int ca;

40     scanf("%d",&ca);

41     while( ca-- ){

42         int n,m;

43         scanf("%d%d",&n,&m);

44         init( n );

45         int a,b;

46         while( m-- ){

47             scanf("%d%d",&a,&b);

48             union_xy( a,b );

49         }

50         int cnt=0;

51         for( int i=1;i<=n;i++ ){

52             if( fa[i]==i )

53                 cnt++;

54         }

55         printf("%d\n",cnt);

56     }

57     return 0;

58 }