LeetCode 1432: Max Difference You Can Get From Changing an Integer

Explanation:

To solve this problem, we need to find the maximum difference we can get by changing an integer num twice following the given rules. We will iterate through the digits of num and for each digit, we will try to find the maximum and minimum possible numbers after changing that digit. Finally, we calculate the maximum difference between these two numbers.

• Algorithm:

  1. Initialize maxDiff to -1.
  2. Convert num to a string for easier manipulation.
  3. Iterate over each digit in the string representation of num.
     • For each digit, try replacing it with all possible digits from 1 to 9 (excluding the current digit) and find the maximum and minimum numbers that can be formed.
     • Update maxDiff with the maximum difference found so far.
  4. Return maxDiff.

• Time Complexity: O(N) where N is the number of digits in num.

• Space Complexity: O(N) for storing the string representation of num.

:

class Solution {
    public int maxDiff(int num) {
        String numStr = String.valueOf(num);
        int maxDiff = -1;
        
        for (int i = 0; i < numStr.length(); i++) {
            char c = numStr.charAt(i);
            for (char replace = '0'; replace <= '9'; replace++) {
                String newNum = numStr.replace(c, replace);
                if (newNum.charAt(0) != '0') {
                    int newInt = Integer.parseInt(newNum);
                    maxDiff = Math.max(maxDiff, newInt - num);
                }
            }
        }
        
        return maxDiff;
    }
}