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[LeetCode] Regular Expression Matching(递归)

时间:2014-08-26 22:52:26      阅读:203      评论:0      收藏:0      [点我收藏+]

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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)

标签:style   blog   color   os   io   strong   for   ar   art   

原文地址:http://www.cnblogs.com/Xylophone/p/3938341.html

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