two pointers

Is Palindrome

func toLower(r byte) byte {
	if r >= 'A' && r <= 'Z' {
		return r + 32
	}
	return r
}
 
func isAlphaNum(r byte) bool {
	return (r >= 'a' && r <= 'z') || (r >= 'A' && r <= 'Z') || (r >= '0' && r <= '9')
}
 
func isPalindrome(s string) bool {
	i, j := 0, len(s)-1
 
	for i < j {
		for i < j && !isAlphaNum(s[i]) {
			i++
		}
		for i < j && !isAlphaNum(s[j]) {
			j--
		}
 
		if toLower(s[i]) != toLower(s[j]) {
			return false
		}
		i++
		j--
	}
 
	return true
}
 

Two Sum - Sorted

func twoSum(numbers []int, target int) []int {
    i := 0
    j := len(numbers) - 1
 
    for i < j {
        sum :=  numbers[i] + numbers[j]
        if sum == target {
            return []int{i+1, j+1}
        }
 
        if sum > target {
            j--
        } else {
            i++
        }
    }
 
    return []int{}
}