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") → false
Thoughts:
- 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