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Solution: Largest Odd Number in String

Understand how to apply a greedy technique to find the largest odd-valued substring in a given numeric string. This lesson guides you through scanning the string from the end, identifying odd digits, and extracting the largest valid substring efficiently with O(n) time and O(1) space complexity.

Statement

You are given a string, num, which represents a large integer. Your task is to find the largest odd-valued integer that can be formed as a non-empty substring of num. Return this odd integer as a string. If no odd integer exists, return an empty string ("").

Note: A substring is a continuous sequence of characters within a string.

Constraints:

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