1903. Largest Odd Number in String

#### QUESTION:

You are given a string num, representing a large integer. Return the largest-valued odd integer (as a string) that is a non-empty substring of num, or an empty string “” if no odd integer exists.

A substring is a contiguous sequence of characters within a string.

Example 1:

``````Input: num = "52"
Output: "5"
Explanation: The only non-empty substrings are "5", "2", and "52". "5" is the only odd number.
``````

Example 2:

``````Input: num = "4206"
Output: ""
Explanation: There are no odd numbers in "4206".
``````

Example 3:

``````Input: num = "35427"
Output: "35427"
Explanation: "35427" is already an odd number.
``````

Constraints:

``````1 <= num.length <= 105
num only consists of digits and does not contain any leading zeros.
``````

#### SOLUTION:

``````class Solution {
func largestOddNumber(_ num: String) -> String {
var _num = num

for n in String(num.reversed()) {
guard Int(String(n))! & 1 == 0 else { break }
_num.removeLast()
}

return _num
}
}
``````