LeetCode OJ: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") → falseisMatch("aa","aa") → trueisMatch("aaa","aa") → falseisMatch("aa", "a*") → trueisMatch("aa", ".*") → trueisMatch("ab", ".*") → trueisMatch("aab", "c*a*b") → true

算法比较精炼

class Solution {public:    bool isMatch(const char *s, const char *p) {        assert(s && p);        if (*p == '\0') return *s == '\0';            // next char is not '*': must match current character        if (*(p+1) != '*') {            assert(*p != '*');            return ((*p == *s) || (*p == '.' && *s != '\0')) && isMatch(s+1, p+1);        }        // next char is '*'        while ((*p == *s) || (*p == '.' && *s != '\0')) {            if (isMatch(s, p+2)) return true;            s++;        }        return isMatch(s, p+2);    }};