missjing/leetcode

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 problem： 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 -------------------------------------------------------------- solution： //正则表达式的匹配问题，动态规划的思想用递归实现 //因为'*'号的连续性，所以每次考虑p+1是否是'*'来将问题逐步缩小。 bool isMatch(const char *s, const char *p) { if(*p == '\0') return *s == '\0'; if(*(p + 1) != '*') { if(*p == *s || ((*p) == '.' && (*s) != '\0')) return isMatch(s + 1, p + 1); return false; } else { while(*p == *s || ((*p) == '.' && (*s) != '\0')) //分别遍历"*"代表1个到若干个字符时是否match { if(isMatch(s, p + 2)) { return true; } s++; } return isMatch(s, p + 2); // "*"代表0个字符时是否match } }