poj2524

简单并查集

View Code

   
     

    
      #include 
    
      <
    
      iostream
    
      >
    
      
#include 
    
      <
    
      cstdio
    
      >
    
      
#include 
    
      <
    
      cstdlib
    
      >
    
      
#include 
    
      <
    
      cstring
    
      >
    
      

    
      using
    
       
    
      namespace
    
       std;


    
      #define
    
       maxn 50004
    
      


    
      int
    
       father[maxn];


    
      int
    
       getanc(
    
      int
    
       a)
{
 
    
      if
    
       (father[a] 
    
      ==
    
       a)
 
    
      return
    
       a;
 
    
      return
    
       father[a] 
    
      =
    
       getanc(father[a]);
}


    
      void
    
       merge(
    
      int
    
       a, 
    
      int
    
       b)
{
 
    
      if
    
       (father[a] 
    
      ==
    
       
    
      -
    
      1
    
      )
 father[a] 
    
      =
    
       a;
 
    
      if
    
       (father[b] 
    
      ==
    
       
    
      -
    
      1
    
      )
 father[b] 
    
      =
    
       b;
 father[getanc(a)] 
    
      =
    
       getanc(b);
}


    
      int
    
       main()
{

    
      //
    
       freopen("t.txt", "r", stdin);
    
      

    
       
    
      int
    
       t 
    
      =
    
       
    
      0
    
      ;
 
    
      int
    
       n, m;
 
    
      while
    
       (scanf(
    
      "
    
      %d%d
    
      "
    
      , 
    
      &
    
      n, 
    
      &
    
      m), n 
    
      |
    
       m)
 {
 memset(father, 
    
      -
    
      1
    
      , 
    
      sizeof
    
      (father));
 t
    
      ++
    
      ;
 
    
      for
    
       (
    
      int
    
       i 
    
      =
    
       
    
      0
    
      ; i 
    
      <
    
       m; i
    
      ++
    
      )
 {
 
    
      int
    
       a, b;
 scanf(
    
      "
    
      %d%d
    
      "
    
      , 
    
      &
    
      a, 
    
      &
    
      b);
 a
    
      --
    
      ;
 b
    
      --
    
      ;
 merge(a, b);
 }
 
    
      int
    
       ans 
    
      =
    
       
    
      0
    
      ;
 
    
      for
    
       (
    
      int
    
       i 
    
      =
    
       
    
      0
    
      ; i 
    
      <
    
       n; i
    
      ++
    
      )
 
    
      if
    
       (father[i] 
    
      ==
    
       
    
      -
    
      1
    
       
    
      ||
    
       father[i] 
    
      ==
    
       i)
 ans
    
      ++
    
      ;
 printf(
    
      "
    
      Case %d: %d\n
    
      "
    
      , t, ans);
 }
 
    
      return
    
       
    
      0
    
      ;
}