Largest Odd Number in String
To solve this problem, we can iterate the characters in the input string in reverse order. If we find an odd digit, we return the substring starting from index 0 to the current index+1. This will ensure that the returned substring is the largest odd number because it includes all the digits from the original number up to the first odd digit found from the right.
Here is the Python code:


The for loop in the solution starts at the end of the string and ends at the beginning of it. When it finds the first odd digit (a digit whose modulo 2 equals 1), it returns a substring of num
that goes from the first character (index 0) to the character at the current index + 1. If the loop ends without finding an odd digit, the function returns an empty string. This happens when all the digits in num
are even.