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LeetCode solutions

2089. Maximum Matrix Sum

My accepted Python solution to LeetCode problem 2089, Maximum Matrix Sum, running in 81ms.

  • Difficulty: Medium
  • Python
  • Runtime 81ms
  • Memory 26.8MB

Read the problem on LeetCode View on GitHub

The problem statement is LeetCode’s and stays on their site. What follows is my accepted solution.

Python

Accepted on LeetCode — runtime 81ms, memory 26.8MB, accepted 2025-12-29.

python
class Solution:
    def maxMatrixSum(self, matrix: List[List[int]]) -> int:
        # Key insight: We can always make all values positive except possibly one
        # If odd number of negatives, we keep the smallest absolute value negative
        # Time: O(n^2), Space: O(1)
        
        total = 0
        min_abs = float('inf')
        neg_count = 0
        
        for row in matrix:
            for val in row:
                total += abs(val)
                min_abs = min(min_abs, abs(val))
                if val < 0:
                    neg_count += 1
        
        # If odd number of negatives, we must keep one value negative
        if neg_count % 2 == 1:
            total -= 2 * min_abs
        
        return total

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