@@ -26,6 +26,7 @@ My solutions to LeetCode problems in Kotlin.
 | [1829](https://leetcode.com/problems/maximum-xor-for-each-query/) | [Maximum XOR for Each Query](src/main/kotlin/com/schmoczer/leetcode/_1829/MaximumXorForEachQuery.kt) | Medium |
 | [1861](https://leetcode.com/problems/rotating-the-box/) | [Rotating the Box](src/main/kotlin/com/schmoczer/leetcode/_1861/RotatingTheBox.kt) | Medium |
 | [1957](https://leetcode.com/problems/delete-characters-to-make-fancy-string/) | [Delete Characters to Make Fancy String](src/main/kotlin/com/schmoczer/leetcode/_1957/DeleteCharactersToMakeFancyString.kt) | Easy |
+| [1975](https://leetcode.com/problems/maximum-matrix-sum/) | [Maximum Matrix Sum](src/main/kotlin/com/schmoczer/leetcode/_1975/MaximumMatrixSum.kt) | Medium |
 | [2064](https://leetcode.com/problems/minimized-maximum-of-products-distributed-to-any-store/) | [Minimized Maximum of Products Distributed to Any Store](src/main/kotlin/com/schmoczer/leetcode/_2064/MinimizedMaximum.kt) | Medium |
 | [2070](https://leetcode.com/problems/most-beautiful-item-for-each-query/) | [Most Beautiful Item for Each Query](src/main/kotlin/com/schmoczer/leetcode/_2070/MostBeautifulItemForEachQuery.kt) | Medium |
 | [2275](https://leetcode.com/problems/largest-combination-with-bitwise-and-greater-than-zero/) | [Largest Combination With Bitwise AND Greater Than Zero](src/main/kotlin/com/schmoczer/leetcode/_2275/LargestCombination.kt) | Medium |

@@ -0,0 +1,45 @@
+package com.schmoczer.leetcode._1975
+
+import kotlin.math.abs
+
+class MaximumMatrixSum {
+// Attempt 1
+fun maxMatrixSum1(matrix: Array<IntArray>): Long {
+val countOfMinus = matrix.sumOf { it.count { it < 0 } }
+var maxSum: Long = 0
+for (row in matrix) {
+for (number in row) {
+maxSum += abs(number)
+}
+}
+return if (countOfMinus % 2 == 0) {
+maxSum
+} else {
+val minNumber = matrix.minOf { it.minOf { abs(it) } }
+maxSum - 2 * minNumber
+}
+}
+
+// Attempt 2: Runtime 9ms Beats 100.00%
+fun maxMatrixSum(matrix: Array<IntArray>): Long {
+var countOfMinus = 0
+var minNumber = Int.MAX_VALUE
+var maxSum: Long = 0
+for (row in matrix) {
+for (number in row) {
+maxSum += abs(number)
+if (number < 0) {
+countOfMinus++
+}
+if (abs(number) < minNumber) {
+minNumber = abs(number)
+}
+}
+}
+return if (countOfMinus % 2 == 0) {
+maxSum
+} else {
+maxSum - 2 * minNumber
+}
+}
+}

@@ -0,0 +1,28 @@
+# Maximum Matrix Sum
+
+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
+
+Example 2:
+
+> Input: matrix = [[1,2,3],[-1,-2,-3],[1,2,3]]
+>
+> Output: 16
+
+Constraints:
+
+- `n == matrix.length == matrix[i].length`
+- `2 <= n <= 250`
+- `-10^5 <= matrix[i][j] <= 10^5`

@@ -0,0 +1,44 @@
+package com.schmoczer.leetcode._1975
+
+import org.junit.jupiter.api.BeforeEach
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class MaximumMatrixSumTest {
+private lateinit var sut: MaximumMatrixSum
+
+@BeforeEach
+fun setUp() {
+sut = MaximumMatrixSum()
+}
+
+@Test
+fun `a 2x2 matrix with max sum of 4`() {
+val input = arrayOf(intArrayOf(1, -1), intArrayOf(-1, 1))
+val expected: Long = 4
+
+val result = sut.maxMatrixSum(input)
+
+assertEquals(expected, result)
+}
+
+@Test
+fun `a 3x3 matrix with max sum of 16`() {
+val input = arrayOf(intArrayOf(1, 2, 3), intArrayOf(-1, -2, -3), intArrayOf(1, 2, 3))
+val expected: Long = 16
+
+val result = sut.maxMatrixSum(input)
+
+assertEquals(expected, result)
+}
+
+@Test
+fun `a 3x3 matrix with all numbers being -10000 has max sum of 70000`() {
+val input = arrayOf(intArrayOf(-10000, -10000, -10000), intArrayOf(-10000, -10000, -10000), intArrayOf(-10000, -10000, -10000))
+val expected: Long = 70000
+
+val result = sut.maxMatrixSum(input)
+
+assertEquals(expected, result)
+}
+}