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 (*p == ‘\0‘) return *s == ‘\0‘; //empty if (*(p + 1) != ‘*‘) {//without * if(!matchFirst(s,p)) return false; return isMatch(s + 1, p + 1); } else { //next: with a * if(isMatch(s, p + 2)) return true; //try the length of 0 while ( matchFirst(s,p) ) //try all possible lengths if (isMatch(++s, p + 2)) return true; } } private: bool matchFirst(const char *s, const char *p){ return (*p == *s || (*p == ‘.‘ && *s != ‘\0‘)); } };
[LeetCode] Regular Expression Matching(递归)
原文：http://www.cnblogs.com/Xylophone/p/3938341.html