Move subproject to avoid IntelliJ module name issues

1 files changed, 97 insertions, 0 deletions

diff --git a/aoc-2021-kotlin/src/Day04.kt b/aoc-2021-kotlin/src/Day04.kt
new file mode 100644
index 0000000..96cdf3b
--- /dev/null
+++ b/aoc-2021-kotlin/src/Day04.kt
@@ -0,0 +1,97 @@
+object Day04 {
+    private class Bingo(private val revealQueue: ArrayDeque<Int>, private val boards: List<Board>) {
+        companion object {
+            fun fromString(input: String): Bingo {
+                val sections = input.trim().split("(\\r?\\n){2}".toRegex())
+
+                val revealQueueString = sections.first()
+                val revealQueue = ArrayDeque(revealQueueString.split(",").map(String::toInt))
+
+                val boards = sections.drop(1).map { Board.fromMatrixString(it) }
+
+                return Bingo(revealQueue, boards)
+            }
+        }
+
+        fun getResults() = sequence {
+            while (revealQueue.isNotEmpty() && boards.any { !it.didWin }) {
+                val number = revealQueue.removeFirst()
+
+                for (board in boards.filter { !it.didWin }) {
+                    board.reveal(number)
+
+                    if (board.didWin) {
+                        yield(board.sumOfUnmarked * number)
+                    }
+                }
+            }
+        }
+
+        private class Board(private var rows: List<List<Square>>) {
+            companion object {
+                fun fromMatrixString(matrixString: String): Board = Board(
+                    matrixString.trim().split("\\r?\\n".toRegex()).map { rowString ->
+                        rowString.trim().split("\\s+".toRegex()).map { squareString ->
+                            Square.Unmarked(squareString.toInt())
+                        }
+                    }
+                )
+
+                private const val SIZE = 5
+
+                private val ROWS = (0 until SIZE).map { row ->
+                    (0 until SIZE).map { square ->
+                        Pair(row, square)
+                    }
+                }
+
+                private val COLUMNS = (0 until SIZE).map { column ->
+                    (0 until SIZE).map { square ->
+                        Pair(square, column)
+                    }
+                }
+
+                private val WINNING_CONFIGURATIONS = ROWS + COLUMNS
+            }
+
+            fun reveal(number: Int) {
+                rows = rows.map { row ->
+                    row.map { square ->
+                        if (square is Square.Unmarked && square.number == number) Square.Marked else square
+                    }
+                }
+            }
+
+            val didWin: Boolean
+                get() = WINNING_CONFIGURATIONS.any { configuration ->
+                    configuration.all { (row, column) -> rows[row][column] is Square.Marked }
+                }
+
+            val sumOfUnmarked: Int
+                get() = rows.fold(0) { rowAcc, row ->
+                    rowAcc + row.fold(0) { squareAcc, square ->
+                        squareAcc + if (square is Square.Unmarked) square.number else 0
+                    }
+                }
+
+            sealed class Square {
+                object Marked : Square()
+                class Unmarked(val number: Int) : Square()
+            }
+        }
+    }
+
+    fun bothParts(input: String) = Bingo.fromString(input).getResults().let { it.first() to it.last() }
+}
+
+fun main() {
+    val testInput = readInputAsString("Day04_test")
+    val testOutput = Day04.bothParts(testInput)
+    check(testOutput.first == 4512)
+    check(testOutput.second == 1924)
+
+    val input = readInputAsString("Day04")
+    val output = Day04.bothParts(input)
+    println(output.first)
+    println(output.second)
+}