1903. Largest Odd Number in String

The idea of this solution is pretty simple, we find the last odd digit, and the number from the beginning of num to that odd digit is the greatest odd number we can get.

If you don’t understand, think “what makes an odd number?” An odd number is a number with its last digit being odd (The last digit can be 1, 3, 5, 7, or 9).

Here is an example to explain this concept:

input: num = "123456"

The expected output would be 12345 because that is the biggest number that is odd.

func largestOddNumber(num string) string {
    for i := len(num) - 1; i >= 0; i-- {
        if int(num[i] - '0') % 2 == 1 {
            return num[: i + 1]
        }
    }
    
    return ""
}