package q125

func isAlphanumeric(c byte) bool {
	return c >= '0' && c <= '9' ||
		c >= 'a' && c <= 'z'
}

func toLower(c byte) byte {
	if c >= 'A' && c <= 'Z' {
		return 'a' + c - 'A'
	}
	return c
}

func isPalindrome(s string) bool {
	conv := make([]byte, 0, len(s))
	for i := range len(s) {
		c := toLower(s[i])
		if isAlphanumeric(c) {
			conv = append(conv, c)
		}
	}

	for i := range len(conv) / 2 {
		if conv[i] != conv[len(conv)-1-i] {
			return false
		}
	}
	return true
}

var _ = isPalindrome