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
注意test:aa,a*;aaa,a*a;aaa,a*ac;

 1 bool isMatch(char* s, char* p) {
 2     if(*p==‘\0‘) return *s==‘\0‘;
 3     if(*(p+1)==‘*‘)
 4     {
 5         while(*s==*p||((*p==‘.‘)&&(*s!=‘\0‘)))
 6         {
 7             if(isMatch(s,p+2)) return true;
 8             s++;
 9         }
10         return isMatch(s,p+2); //若为false,则当s不断++至‘\0’时，无法再次与p匹配，如aa，a*，当s==‘\0‘时，仍需与p+2匹配，输出正确结果
11     }
12     else
13     {
14         if(*s==*p||((*p==‘.‘)&&(*s!=‘\0‘)))
15             return isMatch(s+1,p+1);
16         return false;
17     }
18 }

Regular Expression Matching

原文：http://www.cnblogs.com/zl1991/p/4733382.html