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October 17, 2021 02:36
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Solution to Coursera's Kotlin for Java Developer Week 4 Board Assignment
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| package board | |
| import board.Direction.* | |
| fun createSquareBoard(width: Int): SquareBoard = ConcreteSquareBoard(width) | |
| fun <T> createGameBoard(width: Int): GameBoard<T> = ConcreteGameBoard(createSquareBoard(width)) | |
| private fun Cell.coordinate(direction: Direction) = | |
| when (direction) { | |
| UP -> Pair(i - 1, j) | |
| DOWN -> Pair(i + 1, j) | |
| RIGHT -> Pair(i, j + 1) | |
| LEFT -> Pair(i, j - 1) | |
| } | |
| class ConcreteSquareBoard(override val width: Int): SquareBoard { | |
| private val cells: List<List<Cell>> = List(width) { row -> | |
| List(width) { col -> | |
| Cell(row + 1, col + 1) | |
| } | |
| } | |
| override fun getCellOrNull(i: Int, j: Int): Cell? { | |
| if (i > width || j > width || i < 1 || j < 1) return null | |
| return cells[i - 1][j - 1] | |
| } | |
| override fun getCell(i: Int, j: Int): Cell { | |
| if (i > width) throw IllegalArgumentException("{i} is greater than $width") | |
| if (j > width) throw IllegalArgumentException("{j} is greater than $width") | |
| return getCellOrNull(i, j)!! | |
| } | |
| override fun getAllCells(): Collection<Cell> { | |
| return cells.flatten() | |
| } | |
| override fun getRow(i: Int, jRange: IntProgression): List<Cell> { | |
| if (i > width) throw IllegalArgumentException("{i} is greater than $width") | |
| return jRange.filter { j -> j - 1 in cells[i - 1].indices }.map { j -> cells[i - 1][j - 1] } | |
| } | |
| override fun getColumn(iRange: IntProgression, j: Int): List<Cell> { | |
| if (j > width) throw IllegalArgumentException("{j} is greater than $width") | |
| return iRange.filter { i -> i - 1 in cells.indices }.map { i -> cells[i - 1][j - 1] } | |
| } | |
| override fun Cell.getNeighbour(direction: Direction): Cell? { | |
| val (i, j) = this.coordinate(direction) | |
| return getCellOrNull(i, j) | |
| } | |
| } | |
| class ConcreteGameBoard<T>(private val squareBoard: SquareBoard): GameBoard<T>, SquareBoard by squareBoard { | |
| private val maps: HashMap<Cell, T?> = HashMap() | |
| init { | |
| squareBoard.getAllCells().forEach { | |
| maps[it] = null | |
| } | |
| } | |
| override fun get(cell: Cell): T? { | |
| return maps[cell] | |
| } | |
| override fun set(cell: Cell, value: T?) { | |
| maps.set(cell, value) | |
| } | |
| override fun filter(predicate: (T?) -> Boolean): Collection<Cell> { | |
| return maps.filter { (_, value) -> predicate(value) }.keys | |
| } | |
| override fun find(predicate: (T?) -> Boolean): Cell? { | |
| return filter(predicate).first() | |
| } | |
| override fun any(predicate: (T?) -> Boolean): Boolean { | |
| return maps.any { (_, value) -> predicate(value)} | |
| } | |
| override fun all(predicate: (T?) -> Boolean): Boolean { | |
| return maps.all { (_, value) -> predicate(value) } | |
| } | |
| } |
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haha, just noticed mistakes in the exception throwing code. I should have use $i instead of {i} etc.