Largest Odd Number in String — LeetCode 1903 Python Solution

The 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.

Example

Input

num = "52"

Output

"5"

Explanation

The only non-empty substrings are "5", "2", and "52". "5" is the only odd number.

Python solution

class Solution:
    def largestOddNumber(self, num: str) -> str:
        for i in range(len(num) - 1, -1, -1):
            if (int(num[i]) & 1) == 1:
                return num[: i + 1]
        return ''

Complexity

Pattern: Greedy

Take the locally best option every time — when you can prove that never costs you later. LeetCode 1903. Largest Odd Number in String is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Greedy.

The greedy guide has the Python template for the pattern and the 346 LeetCode problems that use it.

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