Problem Statement

Given a string s containing 0 to 9 digits, create the largest possible palindromic number using the string characters. It should not contain leading zeroes.

A palindromic number reads the same backward as forward.

If it's not possible to form such a number using all digits of the given string, you can skip some of them.

Examples

Example 1

• Input: s = "323211444"
• Expected Output: "432141234"
• Justification: This is the largest palindromic number that can be formed from the given digits.

Example 2

• Input: s = "998877"
• Expected Output: "987789"
• Justification: "987789" is the largest palindrome that can be formed.

Example 3

• Input: s = "54321"
• Expected Output: "5"
• Justification: Only "5" can form a valid palindromic number as other digits cannot be paired.

Constraints:

• 1 <= num.length <= 10⁵
• num consists of digits.

Try it yourself

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