14.字符串hash寻找第一个只出现一次的字符

 1 //char 0-255一共256个
 2 char getonebyhash(char *str)
 3 {
 4     if (str == NULL)
 5     {
 6         return '';
 7     }
 8     char ch = '';
 9     //哈希表设置为0
10     int hashtable[256] = { 0 };
11     //依次获取
12     char *phash = str;
13 
14     //遍历循环字符串数据存放在hash表
15     while (*phash != '')
16     {
17         hashtable[*phash]++;
18         phash++;
19     }
20 
21     //备份首地址，寻找到第一个值为1的字符
22     phash = str;
23     while (*phash != '')
24     {
25         if (hashtable[*phash] == 1)
26         {
27             ch = *phash;
28             break;
29         }
30         phash++;
31     }
32     return ch;
33 
34     
35 }