[LeetCode] Wildcard Matching

Implement wildcard pattern matching with support for '?' and '*'.

'?' Matches any single character.
'*' Matches any sequence of characters (including the empty sequence).

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", "*") → true
isMatch("aa", "a*") → true
isMatch("ab", "?*") → true
isMatch("aab", "c*a*b") → false
class Solution {
public:
    bool isMatch(const char *s, const char *p) {
        const char *ss = s, *star = nullptr;
        while(*s)
        {
            if(*p == '?' || *p == *s)
            {
                p++, s++;
                continue;
            }
            if(*p == '*')
            {
                star = p++;
                ss = s;
                continue;
            }
            if(star)
            {
                s = ++ss;
                p = star + 1;
                continue;
            }
            return false;
        }
        while(*p == '*')    p++;
        return !*p;
    }
};

Analysis:

For each element in s
If *s==*p or *p == ? which means this is a match, then goes to next element s++ p++.
If p=='*', this is also a match, but one or many chars may be available, so let us save this *'s position and the matched s position.
If not match, then we check if there is a * previously showed up,
       if there is no *,  return false;
       if there is an *,  we set current p to the next element of *, and set current s to the next saved s position.

e.g.

abed
?b*d**

a=?, go on, b=b, go on,
e=*, save * position star=3, save s position ss = 3, p++
e!=d,  check if there was a *, yes, ss++, s=ss; p=star+1
d=d, go on, meet the end.
check the rest element in p, if all are *, true, else false;

Note that in char array, the last is NOT NULL, to check the end, use  "*p"  or "*p=='\0'".


你可能感兴趣的:([LeetCode] Wildcard Matching)