【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

思路：从部分推整体。

 1 class Solution {
 2 public:
 3     bool isMatch(const char *s, const char *p) {
 4         if (*p == ‘\0‘) {
 5             return *s == ‘\0‘;
 6         }
 7         if (*s == *p || *p == ‘.‘ && *s != ‘\0‘) {
 8             return *(p + 1) != ‘*‘ ? isMatch(s + 1, p+ 1) :
 9                                      isMatch(s, p + 2) || isMatch(s + 1, p);
10         } else {
11             return *(p + 1) == ‘*‘ && isMatch(s, p + 2);
12         }
13     }
14 };

【Leetcode】Regular Expression Matching

原文：http://www.cnblogs.com/dengeven/p/4009683.html