1903. Largest Odd Number in String

https://leetcode.com/problems/largest-odd-number-in-string

Description

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.

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