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54: Spiral Matrix
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‎README.md‎

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@@ -13,6 +13,7 @@ My solutions to LeetCode problems in Kotlin.
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| [42](https://leetcode.com/problems/trapping-rain-water/) | [Trapping Rain Water](src/main/kotlin/com/schmoczer/leetcode/_0042/TrappingRainWater.kt) | Hard |
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| [48](https://leetcode.com/problems/rotate-image/) | [Rotate Image](src/main/kotlin/com/schmoczer/leetcode/_0048/RotateImage.kt) | Medium |
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| [49](https://leetcode.com/problems/group-anagrams/) | [Group Anagrams](src/main/kotlin/com/schmoczer/leetcode/_0049/GroupAnagrams.kt) | Medium |
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| [54](https://leetcode.com/problems/spiral-matrix/) | [Spiral Matrix](src/main/kotlin/com/schmoczer/leetcode/_0054/SpiralMatrix.kt) | Medium |
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| [73](https://leetcode.com/problems/set-matrix-zeroes/) | [Set Matrix Zeroes](src/main/kotlin/com/schmoczer/leetcode/_0073/SetMatrixZeroes.kt) | Medium |
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| [125](https://leetcode.com/problems/valid-palindrome/) | [Valid Palindrome](src/main/kotlin/com/schmoczer/leetcode/_0125/ValidPalindrome.kt) | Easy |
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| [151](https://leetcode.com/problems/reverse-words-in-a-string/) | [Reverse Words in a String](src/main/kotlin/com/schmoczer/leetcode/_0151/ReverseWordsInString.kt) | Medium |
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# Spiral Matrix
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Given an `m x n` `matrix`, return all elements of the `matrix` in spiral order.
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Example 1:
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> Input: matrix = [[1,2,3],[4,5,6],[7,8,9]]
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>
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> Output: [1,2,3,6,9,8,7,4,5]
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Example 2:
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> Input: matrix = [[1,2,3,4],[5,6,7,8],[9,10,11,12]]
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>
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> Output: [1,2,3,4,8,12,11,10,9,5,6,7]
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Constraints:
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- `m == matrix.length`
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- `n == matrix[i].length`
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- `1 <= m, n <= 10`
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- `-100 <= matrix[i][j] <= 100`
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package com.schmoczer.leetcode._0054
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class SpiralMatrix {
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fun spiralOrder(matrix: Array<IntArray>): List<Int> {
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var leftBoundary = -1
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var upperBoundary = 0
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var rightBoundary = matrix.first().size
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var lowerBoundary = matrix.size
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val result = mutableListOf<Int>()
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fun moveLeft(row: Int, column: Int): Pair<Int, Int> {
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for (i in (leftBoundary + 1 until column + 1).reversed()) {
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result.add(matrix[row][i])
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}
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leftBoundary++
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return Pair(row, leftBoundary)
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}
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fun moveUp(row: Int, column: Int): Pair<Int, Int> {
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for (i in (upperBoundary + 1 until row + 1).reversed()) {
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result.add(matrix[i][column])
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}
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upperBoundary++
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return Pair(upperBoundary, column)
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}
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fun moveRight(row: Int, column: Int): Pair<Int, Int> {
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for (i in column until rightBoundary) {
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result.add(matrix[row][i])
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}
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rightBoundary--
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return Pair(row, rightBoundary)
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}
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fun moveDown(row: Int, column: Int): Pair<Int, Int> {
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for (i in row until lowerBoundary) {
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result.add(matrix[i][column])
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}
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lowerBoundary--
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return Pair(lowerBoundary, column)
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}
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var row = 0
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var column = 0
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while (true) {
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val afterRight = moveRight(row, column)
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if (leftBoundary >= rightBoundary || upperBoundary >= lowerBoundary) break
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val afterDown = moveDown(afterRight.first + 1, afterRight.second)
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if (leftBoundary >= rightBoundary || upperBoundary >= lowerBoundary) break
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val afterLeft = moveLeft(afterDown.first, afterDown.second - 1)
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if (leftBoundary >= rightBoundary || upperBoundary >= lowerBoundary) break
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val afterUp = moveUp(afterLeft.first - 1, afterLeft.second)
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if (leftBoundary >= rightBoundary || upperBoundary >= lowerBoundary) break
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row = afterUp.first
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column = afterUp.second + 1
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}
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return result
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}
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}
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package com.schmoczer.leetcode._0054
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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 SpiralMatrixTest {
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private lateinit var sut: SpiralMatrix
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@BeforeEach
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fun setUp() {
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sut = SpiralMatrix()
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}
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@Test
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fun `spiral a 3x3 matrix`() {
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val input = arrayOf(intArrayOf(1, 2, 3), intArrayOf(4, 5, 6), intArrayOf(7, 8, 9))
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val exptected = listOf(1, 2, 3, 6, 9, 8, 7, 4, 5)
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assertEquals(exptected, sut.spiralOrder(input))
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}
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@Test
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fun `spiral a 4x4 matrix`() {
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val input = arrayOf(intArrayOf(1, 2, 3, 4), intArrayOf(5, 6, 7, 8), intArrayOf(9, 10, 11, 12))
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val expected = listOf(1, 2, 3, 4, 8, 12, 11, 10, 9, 5, 6, 7)
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assertEquals(expected, sut.spiralOrder(input))
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}
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}

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