hoj1878

看是否所有定点的度都是偶数，并使用并查集看图是否连通。我开始因为没有判断是否连通而错了许多次。

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

    
      using
    
       
    
      namespace
    
       std;


    
      #define
    
       maxn 1005
    
      


    
      int
    
       n, m, f[maxn], father[maxn];


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


    
      bool
    
       ok()
{
 
    
      for
    
       (
    
      int
    
       i 
    
      =
    
       
    
      0
    
      ; i 
    
      <
    
       n; i
    
      ++
    
      )
 
    
      if
    
       (f[i] 
    
      %
    
       
    
      2
    
       
    
      !=
    
       
    
      0
    
       
    
      ||
    
       getanc(i) 
    
      !=
    
       getanc(
    
      0
    
      ))
 
    
      return
    
       
    
      false
    
      ;
 
    
      return
    
       
    
      true
    
      ;
}


    
      int
    
       main()
{
 
    
      //
    
      freopen("D:\\t.txt", "r", stdin);
    
      

    
       
    
      while
    
       (scanf(
    
      "
    
      %d
    
      "
    
      , 
    
      &
    
      n) 
    
      !=
    
       EOF 
    
      &&
    
       n 
    
      !=
    
       
    
      0
    
      )
 {
 scanf(
    
      "
    
      %d
    
      "
    
      , 
    
      &
    
      m);
 
    
      for
    
       (
    
      int
    
       i 
    
      =
    
       
    
      0
    
      ; i 
    
      <
    
       n; i
    
      ++
    
      )
 father[i] 
    
      =
    
       i;
 memset(f, 
    
      0
    
      , 
    
      sizeof
    
      (f));
 
    
      for
    
       (
    
      int
    
       i 
    
      =
    
       
    
      0
    
      ; i 
    
      <
    
       m; i
    
      ++
    
      )
 {
 
    
      int
    
       a, b;
 scanf(
    
      "
    
      %d%d
    
      "
    
      , 
    
      &
    
      a, 
    
      &
    
      b);
 a
    
      --
    
      ;
 b
    
      --
    
      ;
 father[getanc(a)] 
    
      =
    
       getanc(b);
 f[a]
    
      ++
    
      ;
 f[b]
    
      ++
    
      ;
 }
 
    
      if
    
       (ok())
 printf(
    
      "
    
      1\n
    
      "
    
      );
 
    
      else
    
      
 printf(
    
      "
    
      0\n
    
      "
    
      );
 }
 
    
      return
    
       
    
      0
    
      ;
}