How do you solve Maximum Difference by Remapping a Digit on LeetCode?

Maximum Difference by Remapping a Digit (LeetCode #2566) can be solved using Brute Force or Optimal Solution. The optimal approach is Optimal Solution with O(n) time complexity and O(n) space complexity. Key insight: The first non-nine digit should be replaced with 9 for maximum value.

What is the brute force solution for Maximum Difference by Remapping a Digit?

The brute force approach for Maximum Difference by Remapping a Digit is Brute Force, with O(n²) time complexity and O(1) space complexity. The brute force approach involves trying every possible digit remapping for both maximum and minimum values. This means for each digit in the number, we will replace it with every other digit and calculate the resulting number. The optimal Optimal Solution approach improves this to O(n).

What algorithm or data structure is used to solve Maximum Difference by Remapping a Digit?

Maximum Difference by Remapping a Digit uses the following concepts: Math, Greedy. The recommended patterns to study are: Greedy, String Manipulation.

What are the interview tips for Maximum Difference by Remapping a Digit?

Clearly explain your thought process when discussing brute force vs. optimal solutions. Be mindful of edge cases, such as numbers with repeated digits. Practice explaining your code as you write it, as this simulates the interview environment.

What are common mistakes when solving Maximum Difference by Remapping a Digit?

Not considering leading zeros when calculating the minimum value. Failing to check all possible digit replacements in the brute force method.

#2566

Maximum Difference by Remapping a Digit

Easy

MathGreedyGreedyString Manipulation

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

	Brute Force	Optimal Solution★
Time	O(n²)	O(n)
Space	O(1)	O(n)

💡

Intuition

Time O(n)Space O(n)

The optimal solution focuses on strategically remapping the first non-nine digit to 9 for the maximum value and the first non-zero digit to 0 for the minimum value. This reduces unnecessary computations and directly targets the digits that will yield the largest difference.

⚙️

Algorithm

4 steps

1Step 1: Convert the number to a string to access each digit.
2Step 2: Identify the first non-nine digit and replace it with 9 to get the maximum value.
3Step 3: Identify the first non-zero digit and replace it with 0 to get the minimum value.
4Step 4: Return the difference between the maximum and minimum values.

solution.py15 lines

1# Full working Python code
2
3def maxDifference(num):
4    num_str = str(num)
5    max_num = num_str
6    min_num = num_str
7    for i in range(len(num_str)):
8        if num_str[i] != '9':
9            max_num = num_str[:i] + '9' + num_str[i+1:]
10            break
11    for i in range(len(num_str)):
12        if num_str[i] != '0':
13            min_num = num_str[:i] + '0' + num_str[i+1:]
14            break
15    return int(max_num) - int(min_num)

ℹ

Complexity note: The complexity is O(n) because we are only iterating through the digits of the number a couple of times, which is linear with respect to the number of digits.

1The first non-nine digit should be replaced with 9 for maximum value.
2The first non-zero digit should be replaced with 0 for minimum value.

Solutions and explanations are original Tejav content. Problem titles © LeetCode — use the LeetCode button above for the full problem statement.