Maximum Difference by Remapping a Digit

You are given an integer num. You know that Bob will sneakily remap one of the 10 possible digits (0 to 9) to another digit.

Return the difference between the maximum and minimum values Bob can make by remapping exactly one digit in num.

Notes:

• When Bob remaps a digit d1 to another digit d2, Bob replaces all occurrences of d1 in num with d2.

• Bob can remap a digit to itself, in which case num does not change.

• Bob can remap different digits for obtaining minimum and maximum values respectively.

• The resulting number after remapping can contain leading zeroes.

LeetCode Problem - 2566

class Solution {
    public int minMaxDifference(int num) {
        // Find the difference between the maximum and minimum possible values
        // formed by modifying digits of the input number.
        return firstNonZeroAndNine(num);
    }

    public int firstNonZeroAndNine(int num) {
        // Convert the number to a string for digit manipulation.
        String strNum = String.valueOf(num);

        // Initialize placeholders for the first non-'9' and non-'0' characters.
        char non9 = '9';
        char non0 = '0';

        // Find the first digit that is not '9' (to replace with '9' later).
        for (int i = 0; i < strNum.length(); i++) {
            char temp = strNum.charAt(i);
            if (non9 != temp) { 
                // Assign the first non-'9' digit found.
                non9 = temp;
                break;
            }
        }

        // Find the first digit that is not '0' (to replace with '0' later).
        for (int i = 0; i < strNum.length(); i++) {
            char temp = strNum.charAt(i);
            if (non0 != temp) { 
                // Assign the first non-'0' digit found.
                non0 = temp;
                break;
            }
        }

        // Replace all occurrences of `non9` with '9' to form the highest number.
        int highest = Integer.parseInt(strNum.replace(non9, '9'));

        // Replace all occurrences of `non0` with '0' to form the lowest number.
        int lowest = Integer.parseInt(strNum.replace(non0, '0'));

        // Return the absolute difference between the highest and lowest numbers.
        return Math.abs(highest - lowest);
    }
}