Maximum Matrix Sum - LeetCode solutions

Problem

You are given an n x n integer matrix. You can do the following operation any number of times:

Choose any two adjacent elements of matrix and multiply each of them by -1.

Two elements are considered adjacent if and only if they share a border.

Your goal is to maximize the summation of the matrix's elements. Return **the *maximum* sum of the matrix's elements using the operation mentioned above.**

Example 1:

Input: matrix = [[1,-1],[-1,1]]
Output: 4
Explanation: We can follow the following steps to reach sum equals 4:
- Multiply the 2 elements in the first row by -1.
- Multiply the 2 elements in the first column by -1.

Example 2:

Input: matrix = [[1,2,3],[-1,-2,-3],[1,2,3]]
Output: 16
Explanation: We can follow the following step to reach sum equals 16:
- Multiply the 2 last elements in the second row by -1.

Constraints:

n == matrix.length == matrix[i].length
2 <= n <= 250
-10^5 <= matrix[i][j] <= 10^5

Solution (Java)

class Solution {
    public long maxMatrixSum(int[][] matrix) {
        int numNegatives = 0;
        long totalSum = 0;
        int minNeg = Integer.MIN_VALUE;
        int minPos = Integer.MAX_VALUE;
        for (int[] ints : matrix) {
            for (int e = 0; e < matrix[0].length; e++) {
                int value = ints[e];
                if (value < 0) {
                    numNegatives++;
                    totalSum = totalSum - value;
                    minNeg = Math.max(value, minNeg);
                } else {
                    totalSum = totalSum + value;
                    minPos = Math.min(value, minPos);
                }
            }
        }

        int min = Math.min(minPos, -minNeg);

        return totalSum - numNegatives % 2 * (min + min);
    }
}

Explain:

nope.

Complexity:

Time complexity : O(n).
Space complexity : O(n).