LeetCode_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

　　

class Solution {
public:
    bool isMatch(const char *s, const char *p) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function    
         assert(s != NULL  && p != NULL);        
        if(*p == '\0') return *s == '\0';
        if(*(p+1) != '*'){
            if(*s == *p || (*p == '.' && *s != '\0') )return isMatch(s+1,p+1);
            return false;
        }else{
            while(*s == *p ||(*p == '.' && *s != '\0')){
                if(isMatch(s,p+2)) //匹配零个
                  return true;
                s++; //匹配多个
            }
            //while 结束后，和*后的进行匹配
            return isMatch(s, p+2) ;            
        }
    }
};

http://www.cnblogs.com/yingzhongwen/archive/2013/04/20/3031915.html