Largest Palindromic Number
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"Use the digits "4449477" from
num to form "7449447", which is the largest palindromic integer that can be formed.Example 2
Input
num = "00009"Output
"9""9" is the largest palindromic integer that can be formed, and the returned integer should not contain leading zeroes.
Constraints
- 1 <= num.length <= 10^5
- num consists of digits.