hdu2024

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      #include
    
      "
    
      iostream
    
      "
    
      

    
      using
    
       
    
      namespace
    
       std;

    
      int
    
       main()
{
 
    
      int
    
       n;
 
    
      char
    
       ch[
    
      1000
    
      ];
 
    
      int
    
       i;
 scanf(
    
      "
    
      %d\n
    
      "
    
      ,
    
      &
    
      n); 
    
      //
    
       cin>>n;cout<<endl;
    
      

    
       
    
      while
    
      (n
    
      --
    
      )
 {
 gets(ch);
 
    
      int
    
       count
    
      =
    
      0
    
      ;
 
    
      if
    
      (
    
      !
    
      (ch[
    
      0
    
      ]
    
      >=
    
      '
    
      a
    
      '
    
      &&
    
      ch[
    
      0
    
      ]
    
      <=
    
      '
    
      z
    
      '
    
      )
    
      &&
    
      ch[
    
      0
    
      ]
    
      !=
    
      '
    
      _
    
      '
    
      &&!
    
      (ch[
    
      0
    
      ]
    
      >=
    
      '
    
      A
    
      '
    
      &&
    
      ch[
    
      0
    
      ]
    
      <=
    
      '
    
      Z
    
      '
    
      )) count
    
      =
    
      1
    
      ;
 
    
      else
    
      
 {
 
    
      for
    
      (i
    
      =
    
      0
    
      ;i
    
      <
    
      strlen(ch);i
    
      ++
    
      )
 {
 
    
      if
    
      (
    
      !
    
      (ch[i]
    
      >=
    
      '
    
      a
    
      '
    
      &&
    
      ch[i]
    
      <=
    
      '
    
      z
    
      '
    
      )
    
      &&!
    
      (ch[i]
    
      >=
    
      '
    
      0
    
      '
    
      &&
    
      ch[i]
    
      <=
    
      '
    
      9
    
      '
    
      )
    
      &&
    
      ch[i]
    
      !=
    
      '
    
      _
    
      '
    
      &&!
    
      (ch[i]
    
      >=
    
      '
    
      A
    
      '
    
      &&
    
      ch[i]
    
      <=
    
      '
    
      Z
    
      '
    
      ))
 {
 count
    
      =
    
      1
    
      ; 
    
      break
    
      ;
 }
 }
 }
 
 
    
      if
    
      (count
    
      ==
    
      0
    
      ) cout
    
      <<
    
      "
    
      yes
    
      "
    
      <<
    
      endl;
 
    
      else
    
       cout
    
      <<
    
      "
    
      no
    
      "
    
      <<
    
      endl;
 }
 
    
      return
    
       
    
      0
    
      ;
}
   
     

http://acm.hdu.edu.cn/showproblem.php?pid=2024 (基础知识)

标识符：字母，数字和下划线组成，以字母或下划线开头