Find the character stream for the first time a character appears only

Topic: Please implement a function to find the character stream for the first time a character appears only. For example, when the character stream reads only the first two characters "go", the first character only occurs once a "g". When reading out the first six characters "google" from the character stream, first appears only one character is "l".

. 1  class Solution
 2  {
 . 3  
. 4      // Method a: 
. 5      #if to false
 . 6      // dictionary storing character keys and the number of occurrences 
. 7      Private the Dictionary < char , int > dict = new new the Dictionary < char , int > ();
 . 8  
. 9      public  char FirstAppearingOnce ()
 10      {
 . 11          // Write code here Wallpaper
 12 is          // traverse the dictionary, the first Key 1 Value is required for the 
13 is          the foreach ( var Itemin dict)
 14          {
 15              IF (item.Value == . 1 )
 16              {
 . 17                  return ( char ) item.Key;
 18 is              }
 . 19          }
 20 is  
21 is          return  ' # ' ;
 22 is      }
 23 is  
24      public  void the Insert ( char C)
 25      {
 26          // the Write code here Wallpaper
 27          // dictionary is empty, adding the first key 
28          IF (dict == null)
 29          {
 30              dict.Add (c, . 1 );
 31 is              return ;
 32          }
 33 is  
34 is          // dictionary whether there is key c, defaults to false 
35          BOOL In Flag = to false ;
 36  
37 [          IF (dict.ContainsKey (C))
 38 is          {
 39              dict [C] + = . 1 ;
 40          }
 41 is          the else 
42 is          {
 43 is              dict.Add (C, . 1 );
 44 is          }
 45      }
46 is      #endif 
47  
48      // Method Two: 
49      / * apply an array of integers of size 256, int [] COUNT = new new int [256] {0};
 50       * initialize 0s
 51 is       * values in the input character as the array index, into a position corresponding to appear in frequency
 52       * declare a list of characters, the recording order of the input character *
 53 is       * / 
54 is      Private  int [] COUNT = new new  int [ 256 ];
 55  
56 is      Private list < char > = List new new List < char > ();
 57 is  
58      public  void the Insert ( char CH)
59      {
 60          // the Write code here Wallpaper
 61 is  
62 is          // if the current character is the first time, the recording order of appearance 
63 is          IF (COUNT [( int ) CH] == 0 )
 64              list.add (CH);
 65  
66          COUNT [( int ) CH] ++ ;
 67      }
 68  
69      public  char FirstAppearingOnce ()
 70      {
 71 is          // the Write code here Wallpaper 
72  
73 is          the foreach ( var Item in List)
 74          {
75             if (count[(int) item] == 1)
76             {
77                 return (char) item;
78             }
79         }
80 
81         return '#';
82     }
83 }