1881. Maximum Value after Insertion

https://leetcode.com/problems/maximum-value-after-insertion

Description

You are given a very large integer n, represented as a string,​​​​​​ and an integer digit x. The digits in n and the digit x are in the inclusive range [1, 9], and n may represent a negative number.

You want to maximize n's numerical value by inserting x anywhere in the decimal representation of n​​​​​​. You cannot insert x to the left of the negative sign.

• For example, if n = 73 and x = 6, it would be best to insert it between 7 and 3, making n = 763.

• If n = -55 and x = 2, it would be best to insert it before the first 5, making n = -255.

Return a string representing the maximum value of n​​​​​​ after the insertion.

Example 1:

**Input:** n = "99", x = 9
**Output:** "999"
**Explanation:** The result is the same regardless of where you insert 9.

Example 2:

**Input:** n = "-13", x = 2
**Output:** "-123"
**Explanation:** You can make n one of {-213, -123, -132}, and the largest of those three is -123.

Constraints:

• 1 <= n.length <= 105

• 1 <= x <= 9

• The digits in n​​​ are in the range [1, 9].

• n is a valid representation of an integer.

• In the case of a negative n,​​​​​​ it will begin with '-'.

ac