Description
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 empty string if no odd integer exists.
Examples
Input:
num = "52"Output:
"5"Explanation:
5 is the only odd number.
Input:
num = "a"Output:
"5"Explanation:
A single-digit number has only one odd digit to consider.
Input:
num = "2468"Output:
""Explanation:
All digits (2, 4, 6, 8) are even numbers, so no odd substring exists. Return empty string.
Constraints
- •
1 ≤ num.length ≤ 10^5