【leetcode】Regular Expression Matching

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) {
 
         if(s==NULL||p==NULL) return false;
         if(*p=='\0'&&*s=='\0') return true;
         if(*p=='\0'&&*s!='\0') return false;
 
         //如果模式串下一个字符为*
         if(*(p+)=='*')
         {
             //循环比较当前字符与模式串字符是否相等
             while((*s!='\0'&&*p=='.')||(*s==*p))
             {
                 //防止这种情况出现："aaa", "a*a"
                 if(isMatch(s,p+)) return true;
                 s++;
             }
             return isMatch(s,p+);
         }
         else if((*s!='\0'&&*p=='.')||*s==*p)
         {
             //如果当前元素相等，则开始匹配下一个元素
             return isMatch(s+,p+);
         }
         return false;
     }
 };