剑指offer——53字符流中第一个只出现一次的字符

 1 class Solution
 2 {
 3 public:
 4     //Insert one char from stringstream
 5     void Insert(char ch)
 6     {
 7         str += ch;
 8         word[ch]++;
 9         if (res == ‘#‘ && word[ch] == 1)//新的字母
10             res = ch;
11         if (word[res] > 1)//重复了
12         {
13             res = ‘#‘;
14             for (int i = index; i < str.length(); ++i)//先后寻找未重复的字母
15             {
16                 if (word[str[i]] == 1)
17                 {
18                     res = str[i];
19                     index = i;
20                     break;
21                 }
22             }
23         }
24     }
25     //return the first appearence once char in current stringstream
26     char FirstAppearingOnce()
27     {
28         return res;
29     }
30 private:
31     string str = "";
32     int word[256] = { 0 };
33     int index = 0;
34     char res = ‘#‘;
35 };