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1975: Maximum Matrix Sum
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‎README.md

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@@ -26,6 +26,7 @@ My solutions to LeetCode problems in Kotlin.
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| [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 |
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| [1861](https://leetcode.com/problems/rotating-the-box/) | [Rotating the Box](src/main/kotlin/com/schmoczer/leetcode/_1861/RotatingTheBox.kt) | Medium |
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| [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 |
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| [1975](https://leetcode.com/problems/maximum-matrix-sum/) | [Maximum Matrix Sum](src/main/kotlin/com/schmoczer/leetcode/_1975/MaximumMatrixSum.kt) | Medium |
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| [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 |
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| [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 |
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| [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 |
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package com.schmoczer.leetcode._1975
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import kotlin.math.abs
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class MaximumMatrixSum {
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// Attempt 1
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fun maxMatrixSum1(matrix: Array<IntArray>): Long {
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val countOfMinus = matrix.sumOf { it.count { it < 0 } }
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var maxSum: Long = 0
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for (row in matrix) {
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for (number in row) {
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maxSum += abs(number)
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}
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}
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return if (countOfMinus % 2 == 0) {
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maxSum
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} else {
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val minNumber = matrix.minOf { it.minOf { abs(it) } }
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maxSum - 2 * minNumber
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}
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}
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// Attempt 2: Runtime 9ms Beats 100.00%
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fun maxMatrixSum(matrix: Array<IntArray>): Long {
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var countOfMinus = 0
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var minNumber = Int.MAX_VALUE
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var maxSum: Long = 0
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for (row in matrix) {
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for (number in row) {
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maxSum += abs(number)
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if (number < 0) {
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countOfMinus++
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}
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if (abs(number) < minNumber) {
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minNumber = abs(number)
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}
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}
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}
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return if (countOfMinus % 2 == 0) {
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maxSum
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} else {
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maxSum - 2 * minNumber
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}
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}
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}
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# Maximum Matrix Sum
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You are given an `n x n` integer `matrix`. You can do the following operation any number of times:
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- Choose any two adjacent elements of `matrix` and multiply each of them by `-1`.
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Two elements are considered adjacent if and only if they share a border.
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Your goal is to maximize the summation of the matrix's elements. Return the maximum sum of the matrix's elements using
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the operation mentioned above.
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Example 1:
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> Input: matrix = [[1,-1],[-1,1]]
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>
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> Output: 4
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Example 2:
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> Input: matrix = [[1,2,3],[-1,-2,-3],[1,2,3]]
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>
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> Output: 16
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Constraints:
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- `n == matrix.length == matrix[i].length`
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- `2 <= n <= 250`
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- `-10^5 <= matrix[i][j] <= 10^5`
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package com.schmoczer.leetcode._1975
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import org.junit.jupiter.api.BeforeEach
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import kotlin.test.Test
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import kotlin.test.assertEquals
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class MaximumMatrixSumTest {
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private lateinit var sut: MaximumMatrixSum
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@BeforeEach
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fun setUp() {
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sut = MaximumMatrixSum()
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}
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@Test
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fun `a 2x2 matrix with max sum of 4`() {
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val input = arrayOf(intArrayOf(1, -1), intArrayOf(-1, 1))
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val expected: Long = 4
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val result = sut.maxMatrixSum(input)
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assertEquals(expected, result)
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}
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@Test
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fun `a 3x3 matrix with max sum of 16`() {
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val input = arrayOf(intArrayOf(1, 2, 3), intArrayOf(-1, -2, -3), intArrayOf(1, 2, 3))
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val expected: Long = 16
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val result = sut.maxMatrixSum(input)
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assertEquals(expected, result)
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}
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@Test
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fun `a 3x3 matrix with all numbers being -10000 has max sum of 70000`() {
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val input = arrayOf(intArrayOf(-10000, -10000, -10000), intArrayOf(-10000, -10000, -10000), intArrayOf(-10000, -10000, -10000))
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val expected: Long = 70000
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val result = sut.maxMatrixSum(input)
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assertEquals(expected, result)
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}
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}

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