LeetCode in Kotlin

44. Wildcard Matching

Hard

Given an input string (s) and a pattern (p), implement wildcard pattern matching with support for '?' and '*' where:

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

The matching should cover the entire input string (not partial).

Example 1:

Input: s = “aa”, p = “a”

Output: false

Explanation: “a” does not match the entire string “aa”.

Example 2:

Input: s = “aa”, p = “*”

Output: true

Explanation: ‘*’ matches any sequence.

Example 3:

Input: s = “cb”, p = “?a”

Output: false

Explanation: ‘?’ matches ‘c’, but the second letter is ‘a’, which does not match ‘b’.

Constraints:

• 0 <= s.length, p.length <= 2000
• s contains only lowercase English letters.
• p contains only lowercase English letters, '?' or '*'.

Solution

class Solution {
    fun isMatch(s: String, p: String): Boolean {
        var i = 0
        var j = 0
        var starIdx = -1
        var lastMatch = -1
        while (i < s.length) {
            if (j < p.length &&
                (s[i] == p[j] || p[j] == '?')
            ) {
                i++
                j++
            } else if (j < p.length && p[j] == '*') {
                starIdx = j
                lastMatch = i
                j++
            } else if (starIdx != -1) {
                // there is a no match and there was a previous star, we will reset the j to indx
                // after star_index
                // lastMatch will tell from which index we start comparing the string if we
                // encounter * in pattern
                j = starIdx + 1
                // we are saying we included more characters in * so we incremented the
                lastMatch++
                // index
                i = lastMatch
            } else {
                return false
            }
        }
        var isMatch = true
        while (j < p.length && p[j] == '*') {
            j++
        }
        if (i != s.length || j != p.length) {
            isMatch = false
        }
        return isMatch
    }
}

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