algoadvance

Leetcode 2566. Maximum Difference by Remapping a Digit

Problem Statement

You are given an integer num consisting of exactly four digits. You need to find and return the maximum possible difference you can achieve by remapping exactly one digit (0-9) to another digit (0-9). Remapping a digit means replacing all occurrences of it in the number with the new digit.

Clarifying Questions

  1. Can num be negative, or is it guaranteed to be a positive four-digit integer?
    • It is guaranteed to be a positive four-digit integer.
  2. Can the remapped digit be the same as the original digit?
    • While this is technically possible, it will not contribute to maximizing the difference. So, in practice, we would always choose a different digit for the remapping.
  3. Should we consider remapping leading zeros?
    • No, remapping should keep the result as a four-digit number.

Strategy

To solve the problem optimally:

  1. Identify Digits to Remap: We iterate through each digit of the number and consider it as a candidate for remapping.
  2. Compute Results: For each digit in the number, generate the new versions of the number by replacing it with digits 0-9, except for the digit itself.
  3. Calculate Difference: Calculate the possible differences by remapping, and keep track of the maximum difference encountered.

Code

Here is a simple and efficient approach implemented in Java:

public class MaximumDifferenceByRemappingDigit {
    public static int minMaxDifference(int num) {
        String numStr = Integer.toString(num);
        int maxDifference = Integer.MIN_VALUE;

        for (char c = '0'; c <= '9'; c++) {
            // Skip digit if it is not in the number
            if (numStr.indexOf(c) == -1) continue;
            
            // Perform remapping for max
            String maxStr = numStr.replace(c, '9');
            int maxVal = Integer.parseInt(maxStr);
            
            // Perform remapping for min
            String minStr = numStr.replace(c, '0');
            int minVal = Integer.parseInt(minStr);
            
            // Calculate difference
            int currentDifference = maxVal - minVal;

            // update maxDifference
            maxDifference = Math.max(maxDifference, currentDifference);
        }

        return maxDifference;
    }

    public static void main(String[] args) {
        System.out.println(minMaxDifference(1234)); // Example test case, should output the max difference
    }
}

Time Complexity

This approach efficiently finds the maximum possible difference by systematically remapping each digit and considering all valid new values.

Cut your prep time in half and DOMINATE your interview with AlgoAdvance AI