AoC 2015, day 6.

src/aoc2015/Day06.kt

@@ -0,0 +1,52 @@
+package aoc2015
+
+import CharGrid
+import println
+import readInput
+
+/*
+--- Day 6: Probably a Fire Hazard ---
+https://adventofcode.com/2015/day/6
+*/
+fun main() {
+
+    fun part1(input: List<String>): Int {
+        val grid = CharGrid(1000, 1000)
+        input.forEach {
+            val (op, x1, y1, x2, y2) = "(toggle|turn off|turn on) (\\d+),(\\d+) through (\\d+),(\\d+)".toRegex().matchEntire(it)!!.destructured
+            for (y in y1.toInt()..y2.toInt()) {
+                for (x in x1.toInt()..x2.toInt()) {
+                    grid[x, y] = when (op) {
+                        "turn on" -> '*'
+                        "turn off" -> ' '
+                        "toggle" -> if (grid[x, y] == '*') ' ' else '*'
+                        else -> throw IllegalStateException()
+                    }
+                }
+            }
+        }
+        return grid.generateGridPos().count { grid[it] == '*' }
+    }
+
+    fun part2(input: List<String>): Int {
+        val grid = IntArray(1000 * 1000)
+        input.forEach {
+            val (op, x1, y1, x2, y2) = "(toggle|turn off|turn on) (\\d+),(\\d+) through (\\d+),(\\d+)".toRegex().matchEntire(it)!!.destructured
+            for (y in y1.toInt()..y2.toInt()) {
+                for (x in x1.toInt()..x2.toInt()) {
+                    grid[x + y * 1000] = (grid[x + y * 1000] + when (op) {
+                        "turn on" -> 1
+                        "turn off" -> -1
+                        "toggle" -> 2
+                        else -> throw IllegalStateException()
+                    }).coerceAtLeast(0)
+                }
+            }
+        }
+        return grid.sum()
+    }
+
+    val input = readInput("aoc2015/Day06")
+    part1(input).println()
+    part2(input).println()
+}