154. Regular Expression Matching

Description

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

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

The matching should cover theentireinput string (not partial).

The function prototype should be:

bool isMatch(string s, string p)

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 这里c*代表0个c，于是是true

Example

Example 1:

Input："aa"，"a"

Output：false

Explanation：

unable to match

Example 2:

Input："aa"，"a*"

Output：true

Explanation：

'*' can repeat a

思路：

和192题类似，就是思考起来有点麻烦，尤其是source为空时，对于pattern模式的判断，还有pattern第二个为*号时的处理。

代码：