Regular Expression Matching

Implement regular expression matching with support for '.' and '*'.

'.' Matches any single character.
'*' Matches zero or more of the preceding element.

The matching should cover the entire input string (not partial).

The function prototype should be:
bool isMatch(const char *s, const char *p)

Some examples:
isMatch("aa","a") → false
isMatch("aa","aa") → true
isMatch("aaa","aa") → false
isMatch("aa", "a*") → true
isMatch("aa", ".*") → true
isMatch("ab", ".*") → true
isMatch("aab", "c*a*b") → true

思路：

代码：

 1     bool isMatch(const char *s, const char *p) {
 2         // IMPORTANT: Please reset any member data you declared, as
 3         // the same Solution instance will be reused for each test case.  
 4         if(*p == '\0')
 5             return *s == '\0';
 6         if(*(p+1) == '*'){
 7             for(const char *t = s; *t != '\0' && (*t == *p || *p == '.'); t++){
 8                 if(isMatch(t+1, p+2))
 9                     return true;
10             }
11             return isMatch(s, p+2);
12         }
13         else{
14             if(*s != '\0' && (*s == *p || *p == '.'))
15                 return isMatch(s+1, p+1);
16             return false;
17         }
18     }

 

posted on 2013-11-25 17:04  waruzhi  阅读(173)  评论(0)    收藏  举报

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