Largest Odd Number in String - LeetCode solutions

Problem

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 <= 10^5
num only consists of digits and does not contain any leading zeros.

Solution (Java)

class Solution {
    public String largestOddNumber(String num) {
        for (int i = num.length() - 1; i >= 0; i--) {
            if (Integer.parseInt("" + num.charAt(i)) % 2 == 1) {
                return num.substring(0, i + 1);
            }
        }
        return "";
    }
}

Explain:

nope.

Complexity:

Time complexity : O(n).
Space complexity : O(n).