def is_palindrome_range(s: str, left: int, right: int) -> bool:
    while left < right:
        if s[left] != s[right]:
            return False
        left += 1
        right -= 1
    return True

def valid_palindrome(s: str) -> bool:
    left, right = 0, len(s) - 1
    while left < right:
        if s[left] != s[right]:
            # try skipping either the left or right character
            return (is_palindrome_range(s, left + 1, right) or
                    is_palindrome_range(s, left, right - 1))
        left += 1
        right -= 1
    return True

# Time: O(n), Space: O(1)
# "abca"  -> True (delete 'c')
# "raceacar" -> True (delete first 'a')
# "abc"   -> False

Arrays & Strings — Patterns

Arrays & Strings — Patterns

Arrays & Strings — Patterns