Leetcode #2566: Maximum Difference by Remapping a Digit
In this guide, we solve Leetcode #2566 Maximum Difference by Remapping a Digit in Python and focus on the core idea that makes the solution efficient.
You will see the intuition, the step-by-step method, and a clean Python implementation you can use in interviews.
Problem Statement
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.
Quick Facts
- Difficulty: Easy
- Premium: No
- Tags: Greedy, Math
Intuition
A locally optimal choice leads to a globally optimal result for this structure.
That means we can commit to decisions as we scan without backtracking.
Approach
Sort or preprocess if needed, then repeatedly take the best available local choice.
Maintain the minimal state necessary to validate the greedy decision.
Steps:
- Sort or preprocess as needed.
- Iterate and pick the best local option.
- Track the current solution.
Example
Input: num = 11891
Output: 99009
Explanation:
To achieve the maximum value, Bob can remap the digit 1 to the digit 9 to yield 99899.
To achieve the minimum value, Bob can remap the digit 1 to the digit 0, yielding 890.
The difference between these two numbers is 99009.
Python Solution
class Solution:
def minMaxDifference(self, num: int) -> int:
s = str(num)
mi = int(s.replace(s[0], '0'))
for c in s:
if c != '9':
return int(s.replace(c, '9')) - mi
return num - mi
Complexity
The time complexity is , and the space complexity is . The space complexity is .
Edge Cases and Pitfalls
Watch for boundary values, empty inputs, and duplicate values where applicable. If the problem involves ordering or constraints, confirm the invariant is preserved at every step.
Summary
This Python solution focuses on the essential structure of the problem and keeps the implementation interview-friendly while meeting the constraints.