44. 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") → falseThoughts:
- Keep track of last current input string position, current pattern string position and last asterisk (*) position. 
- O(n + m) without extra space 
- LeetCode: 44. Wildcard Matching, Wildcard Pattern Matching @ GeeksforGeeks and String Matching with Wildcards @ Hackerrank 
Code (C):
 bool isMatch(const char *s, const char *p) {
        const char* star=NULL;
        const char* ss=s;
        while (*s){
            //advancing both pointers when (both characters match) or ('?' found in pattern)
            //note that *p will not advance beyond its length 
            if ((*p=='?')||(*p==*s)){s++;p++;continue;} 
            // * found in pattern, track index of *, only advancing pattern pointer 
            if (*p=='*'){star=p++; ss=s;continue;} 
            //current characters didn't match, last pattern pointer was *, current pattern pointer is not *
            //only advancing pattern pointer
            if (star){ p = star+1; s=++ss;continue;} 
           //current pattern pointer is not star, last patter pointer was not *
           //characters do not match
            return false;
        }
       //check for remaining characters in pattern
        while (*p=='*'){p++;}
        return !*p;  
    }Code
Last updated
Was this helpful?