You are given a string num consisting of digits from $0$ to $9$. Your task is to return the largest possible palindromic number as a string by using some or all of the digits in num. The resulting palindromic number must not have leading zeros.

Note: You may reorder the digits freely, and you must use at least one digit from the num string.

Constraints:

• $1\leq$ num.length $\leq 1000$

• num consists of digits

We will use the greedy pattern to solve this problem. The goal is to maximize the size of the palindrome by making locally optimal choices at each step. Specifically, we aim to form the largest possible palindrome by first prioritizing using the highest digits.

The process begins by ...