#2384

Largest Palindromic Number

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Description

You are given a string num consisting of digits only.

Return the largest palindromic integer (in the form of a string) that can be formed using digits taken from num. It should not contain leading zeroes.

Notes:

- You do not need to use all the digits of num, but you must use at least one digit.

- The digits can be reordered.

Example 1:

Input: num = "444947137"

Output: "7449447"

Explanation:

Use the digits "4449477" from "444947137" to form the palindromic integer "7449447".

It can be shown that "7449447" is the largest palindromic integer that can be formed.

Example 2:

Input: num = "00009"

Output: "9"

Explanation:

It can be shown that "9" is the largest palindromic integer that can be formed.

Note that the integer returned should not contain leading zeroes.

Solution