LeetCode in Kotlin

1975. Maximum Matrix Sum

Medium

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
• -105 <= matrix[i][j] <= 105

Solution

class Solution {
    fun maxMatrixSum(matrix: Array<IntArray>): Long {
        var numNegatives = 0
        var totalSum: Long = 0
        var minNeg = Int.MIN_VALUE
        var minPos = Int.MAX_VALUE
        for (ints in matrix) {
            for (e in matrix[0].indices) {
                val value = ints[e]
                if (value < 0) {
                    numNegatives++
                    totalSum = totalSum - value
                    minNeg = Math.max(value, minNeg)
                } else {
                    totalSum = totalSum + value
                    minPos = Math.min(value, minPos)
                }
            }
        }
        val min = Math.min(minPos, -minNeg)
        return totalSum - numNegatives % 2 * (min + min)
    }
}

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