52、剑指offer--正则表达式匹配

 1 class Solution {
 2 public:
 3     bool match(char* str, char* pattern)
 4     {
 5         if(str == NULL || pattern == NULL)
 6         {
 7             return false;
 8         }
 9         return matchCore(str,pattern);
10     }
11     bool matchCore(char *str, char *pattern)
12     {
13         if(*str == ‘\0‘ && *pattern == ‘\0‘)
14             return true;
15         if(*str != ‘\0‘ && *pattern == ‘\0‘)
16             return false;
17         if(*(pattern+1) == ‘*‘)//下一位为*(注意优先级问题加())
18         {
19             if(*pattern == *str || (*pattern == ‘.‘ && *str != ‘\0‘))//当前位匹配
20             {
21                 return matchCore(str+1,pattern+2)//匹配一个
22                     || matchCore(str+1,pattern)//匹配>=2个
23                     || matchCore(str,pattern+2);//匹配0个
24             }
25             else
26             {
27                 return matchCore(str,pattern+2);//匹配0个
28             }
29         }
30         if(*str == *pattern ||(*pattern == ‘.‘ && *str !=‘\0‘))
31             return matchCore(str+1,pattern+1);
32         return false;
33     }
34 };