a little 2019

advent/src/main/kotlin/org/elwaxoro/advent/Coordinates.kt

@@ -94,7 +94,7 @@ data class Coord(val x: Int = 0, val y: Int = 0, val d: Char? = null) {
         /**
          * "x,y" string to coord
          */
-        fun parse(str: String) = str.replace("(","").replace(")","").split(",").map { it.trim() }.let {
+        fun parse(str: String) = str.replace("(", "").replace(")", "").split(",").map { it.trim() }.let {
             Coord(it[0].toInt(), it[1].toInt())
         }
     }
@@ -234,6 +234,30 @@ data class Coord(val x: Int = 0, val y: Int = 0, val d: Char? = null) {
      * Equals check that ignores 'd' and just compares x,y values
      */
     fun equalsCoord(coord: Coord) = x == coord.x && y == coord.y
+
+    /**
+     * Gets the cardinal direction towards the other coord
+     * If other coord is not exactly in any direction, an exception is thrown
+     * If other coord is at the same position, an exception is thrown
+     */
+    fun dirTo(that: Coord): Dir =
+        if (x == that.x && y == that.y) {
+            throw IllegalStateException("No direction possible: $this == $that ")
+        } else if (x == that.x) {
+            if (y < that.y) {
+                Dir.N
+            } else {
+                Dir.S
+            }
+        } else if (y == that.y) {
+            if (x < that.x) {
+                Dir.E
+            } else {
+                Dir.W
+            }
+        } else {
+            throw IllegalStateException("No direction possible: $this vs $that")
+        }
 }
 
 /**
@@ -595,7 +619,7 @@ fun List<LCoord>.shoelaceArea(): Double {
     for (i in 0 until n - 1) {
         a += this[i].x * this[i + 1].y - this[i + 1].x * this[i].y
     }
-    return abs(a + this[n - 1].x * this[0].y -this[0].x * this[n - 1].y) / 2.0
+    return abs(a + this[n - 1].x * this[0].y - this[0].x * this[n - 1].y) / 2.0
 }
 
 /**

advent/src/test/kotlin/org/elwaxoro/advent/y2019/Dec15.kt

@@ -0,0 +1,125 @@
+package org.elwaxoro.advent.y2019
+
+import kotlinx.coroutines.runBlocking
+import org.elwaxoro.advent.Coord
+import org.elwaxoro.advent.Dir
+import org.elwaxoro.advent.PuzzleDayTester
+
+/**
+ * Day 15: Oxygen System
+ */
+class Dec15 : PuzzleDayTester(15, 2019) {
+
+    /**
+     * drive a repair droid around randomly, using intcode program to control it
+     * program loop:
+     * 1. movement input
+     * 2. status output
+     * inputs: 1 (N), 2 (S), 3 (E), 4(W)
+     * outputs: 0 (wall), 1 (moved), 2 (oxygen system)
+     */
+    override fun part1(): Any = runBlocking {
+        val droid = RepairDroid(loadToLong(delimiter = ","))
+        droid.explore()
+        //println(droid.coords.map { it.key.copyD(it.value) }.printify(empty = ' '))
+        droid.stack.size - 1
+    } == 212
+
+    /**
+     * fully explore the maze, then flood fill starting from the oxygen system (BFS)
+     */
+    override fun part2(): Any = runBlocking {
+        val droid = RepairDroid(loadToLong(delimiter = ","), exploreFully = true)
+        droid.explore()
+        val oxygenSystem = droid.coords.firstNotNullOf { cc -> cc.key.takeIf { cc.value == 'E' } }
+        val queue = mutableListOf(oxygenSystem to 0)
+        val visited = droid.coords.filter { it.value == '#' }.keys.toMutableSet()
+        var maxDist = 0
+        while (queue.isNotEmpty()) {
+            val (c, d) = queue.removeFirst()
+            if (d > maxDist) {
+                maxDist = d
+            }
+            visited.add(c)
+            c.neighbors().filter { n -> !visited.contains(n) && queue.none { it.first == n } }.map { n ->
+                queue.add(n to d + 1)
+            }
+        }
+        maxDist
+    } == 358
+
+    /**
+     * droid position is last coord in stack
+     * start position is 0,0
+     * droid explores in a DFS fashion
+     */
+    private class RepairDroid(
+        val code: List<Long>,
+        val coords: MutableMap<Coord, Char> = mutableMapOf(Coord(0, 0) to '.'),
+        val stack: MutableList<Coord> = mutableListOf(Coord(0, 0)),
+        val exploreFully: Boolean = false,
+    ) {
+
+        fun Dir.toLong(): Long =
+            when (this) {
+                Dir.N -> 1
+                Dir.S -> 2
+                Dir.E -> 3
+                Dir.W -> 4
+            }
+
+        fun getInput(): Long =
+            if (stack.isEmpty()) {
+                Long.MAX_VALUE
+            } else {
+                val check = stack.last()
+                if (!exploreFully && coords[check] == 'E') {
+                    // part 1: stop as soon as the stack reaches E for the first time
+                    Long.MAX_VALUE
+                } else {
+                    val options = check.neighbors().filterNot { coords.containsKey(it) }
+                    if (options.isEmpty()) {
+                        // can't explore meaningfully in any directions, we know what everything is already, time to backtrack
+                        stack.removeLast()
+                        if (stack.isEmpty()) {
+                            Long.MAX_VALUE
+                        } else {
+                            check.dirTo(stack.last()).toLong()
+                        }
+                    } else {
+                        // pick any of the options, add it to the stack and attempt to move in that direction
+                        val moveTo = options.first()
+                        stack.add(moveTo)
+                        check.dirTo(moveTo).toLong()
+                    }
+                }
+            }
+
+        fun readOutput(value: Long) {
+            when (value) {
+                0L -> {
+                    val wall = stack.removeLast()
+                    coords[wall] = '#'
+                }
+
+                1L -> {
+                    val open = stack.last()
+                    coords[open] = '.'
+                }
+
+                2L -> {
+                    val oxygenSystem = stack.last()
+                    coords[oxygenSystem] = 'E'
+                }
+            }
+        }
+
+        suspend fun explore() {
+            ElfCode(code).runner(
+                setup = ElfCode.memExpander(10000),
+                input = { getInput() },
+                output = { readOutput(it) }
+            )
+        }
+    }
+}

advent/src/test/kotlin/org/elwaxoro/advent/y2019/ElfCode.kt

@@ -9,6 +9,7 @@ import org.elwaxoro.advent.takeSplit
  * Dec 7: added async support (suspend functions for input / output to allow channels)
  * Dec 9: added relative mode, expanding memory (use setup function to expand manually)
  * Dec 11: added optional exit support, in case input/output are channels
+ * Dec 15: added custom input spike to terminate early (Long.MAX_VALUE)
  */
 class ElfCode(
     private val originalProgram: List<Long>,
@@ -53,8 +54,14 @@ class ElfCode(
                 }
 
                 3 -> { // input
-                    put(1, input.invoke())
-                    idx += 2
+                    val i = input.invoke()
+                    if (i == Long.MAX_VALUE) {
+                        // custom input break
+                        isRunning = false
+                    } else {
+                        put(1, i)
+                        idx += 2
+                    }
                 }
 
                 4 -> { // output

advent/src/test/resources/2019/Dec15.txt

@@ -0,0 +1 @@
+3,1033,1008,1033,1,1032,1005,1032,31,1008,1033,2,1032,1005,1032,58,1008,1033,3,1032,1005,1032,81,1008,1033,4,1032,1005,1032,104,99,101,0,1034,1039,1002,1036,1,1041,1001,1035,-1,1040,1008,1038,0,1043,102,-1,1043,1032,1,1037,1032,1042,1105,1,124,1001,1034,0,1039,1001,1036,0,1041,1001,1035,1,1040,1008,1038,0,1043,1,1037,1038,1042,1105,1,124,1001,1034,-1,1039,1008,1036,0,1041,1001,1035,0,1040,101,0,1038,1043,102,1,1037,1042,1106,0,124,1001,1034,1,1039,1008,1036,0,1041,1001,1035,0,1040,101,0,1038,1043,1001,1037,0,1042,1006,1039,217,1006,1040,217,1008,1039,40,1032,1005,1032,217,1008,1040,40,1032,1005,1032,217,1008,1039,9,1032,1006,1032,165,1008,1040,9,1032,1006,1032,165,1101,2,0,1044,1106,0,224,2,1041,1043,1032,1006,1032,179,1102,1,1,1044,1105,1,224,1,1041,1043,1032,1006,1032,217,1,1042,1043,1032,1001,1032,-1,1032,1002,1032,39,1032,1,1032,1039,1032,101,-1,1032,1032,101,252,1032,211,1007,0,73,1044,1105,1,224,1101,0,0,1044,1106,0,224,1006,1044,247,101,0,1039,1034,102,1,1040,1035,102,1,1041,1036,1002,1043,1,1038,1001,1042,0,1037,4,1044,1106,0,0,57,60,59,78,42,22,33,69,5,77,92,10,55,22,99,62,27,32,75,13,82,48,40,83,95,38,62,65,70,77,79,61,2,47,27,84,46,48,16,15,87,87,23,95,97,16,93,79,27,7,98,97,76,44,6,75,85,51,8,91,94,99,35,28,84,67,83,82,1,80,40,99,81,92,41,97,87,28,81,52,93,37,27,85,76,4,18,80,96,61,83,16,90,86,77,8,76,55,51,61,72,90,90,5,96,75,13,56,40,82,11,97,21,55,95,17,93,97,16,91,30,77,28,32,77,96,49,13,97,30,14,26,93,61,18,32,85,95,81,65,98,49,65,84,46,19,81,45,76,22,88,79,63,84,60,24,37,4,34,80,98,61,95,46,88,99,76,3,92,75,12,95,9,98,94,57,41,77,52,17,80,83,17,83,59,87,85,2,95,88,41,32,98,72,95,23,91,83,65,82,47,90,17,81,67,81,6,90,61,44,85,40,85,19,82,26,86,1,74,62,6,75,98,93,12,84,11,38,57,88,91,76,66,43,46,84,38,48,99,57,20,97,34,72,75,47,94,33,83,82,55,76,34,90,9,74,34,87,18,84,57,38,76,3,31,87,77,2,86,15,23,92,37,20,75,94,27,88,90,87,28,84,31,92,15,75,14,10,82,48,99,49,79,4,96,91,30,16,78,7,75,67,98,1,75,49,70,87,95,89,30,54,31,92,71,57,39,79,19,55,85,25,92,4,23,77,74,77,89,40,39,77,87,39,44,81,98,80,94,29,40,88,69,74,92,54,2,1,83,30,87,85,15,80,97,94,15,93,89,71,69,86,81,75,56,92,58,95,51,93,29,82,79,24,82,9,46,5,88,53,75,90,31,6,91,69,88,8,10,23,67,5,85,78,71,36,98,19,98,53,66,43,17,91,62,28,86,44,79,33,91,79,66,71,86,98,86,60,83,44,94,96,29,85,89,50,85,98,14,8,43,5,75,62,89,90,33,30,86,48,75,99,88,82,45,99,38,60,76,69,45,89,27,93,71,84,96,15,52,85,58,97,99,20,5,79,75,33,80,84,63,87,1,77,31,44,49,99,79,3,83,16,91,42,7,99,66,82,93,76,31,55,77,30,45,88,3,81,53,30,95,24,90,96,26,33,93,32,40,25,76,21,75,17,89,31,81,18,29,97,72,60,90,14,99,93,9,55,92,26,86,28,99,93,1,98,86,60,26,68,95,7,17,86,94,48,68,95,94,88,86,67,82,77,55,76,68,79,76,65,76,21,23,78,28,82,75,23,84,74,67,69,83,70,93,38,75,81,61,87,23,86,92,43,13,23,81,65,65,76,41,34,95,64,89,90,72,79,16,47,84,47,28,83,74,1,41,59,87,84,34,32,94,4,78,37,17,99,86,91,58,97,69,26,93,41,81,36,78,80,18,79,96,51,37,74,45,94,54,98,90,74,27,8,89,79,81,71,60,88,40,86,33,95,98,21,13,9,20,94,48,82,42,69,15,84,45,89,42,98,99,72,72,84,86,54,80,74,68,74,5,85,80,75,34,29,98,16,85,16,86,13,25,74,95,51,86,90,28,81,90,20,70,7,89,37,74,28,86,29,81,95,66,1,64,83,85,27,74,4,69,54,79,66,50,96,43,94,95,45,52,83,17,37,88,85,55,35,66,78,66,86,4,92,2,99,35,89,13,76,71,81,92,96,18,85,68,95,61,97,76,82,66,85,99,82,6,93,31,81,76,80,27,95,38,94,85,98,41,91,0,0,21,21,1,10,1,0,0,0,0,0,0