Max Difference You Can Get From Changing an Integer

Medium

You receive an integer num. You will apply the following steps to num two separate times:

Pick a digit x (0 <= x <= 9).
Pick another digit y (0 <= y <= 9). Note y can be equal to x.
Replace all the occurrences of x in the decimal representation of num by y.

Let a and b be the two results from applying the operation to num independently.

Find and provide the max difference between a and b.

Note that neither a nor b may have any leading zeros, and must not be 0.

Example 1

Input: num = 555

Output: 888

Explanation: The first time pick x = 5 and y = 9 and store the new integer in a.

The second time pick x = 5 and y = 1 and store the new integer in b.

We have now a = 999 and b = 111 and max difference = 888

Example 2

Input: num = 9

Output: 8

Explanation: The first time pick x = 9 and y = 9 and store the new integer in a.

The second time pick x = 9 and y = 1 and store the new integer in b.

We have now a = 9 and b = 1 and max difference = 8

Constraints

Responses stay private.