Day 6 part 2 completed.

day06.kts

@@ -3,8 +3,7 @@ import java.io.File
 import java.lang.RuntimeException
 import java.util.Scanner
 
-data class MoveResult(val newLocation: Pair<Int, Int>, val newDirection: Direction)
-data class MoveHistory(val location: Pair<Int, Int>, val direction: Direction)
+data class LocationState(val location: Pair<Int, Int>, val direction: Direction)
 enum class Direction(val offset: Pair<Int, Int>) {
     NORTH(Pair(0, -1)),
     EAST(Pair(1, 0)),
@@ -36,12 +35,12 @@ enum class Direction(val offset: Pair<Int, Int>) {
     fun moveByPartOneRules(
         currentLocation: Pair<Int, Int>,
         blocks: Set<Pair<Int, Int>>
-    ): MoveResult {
+    ): LocationState {
         var currentDirection = this
         do {
             val potentialMove = currentDirection.move(currentLocation)
             if (potentialMove !in blocks) {
-                return MoveResult(potentialMove, currentDirection)
+                return LocationState(potentialMove, currentDirection)
             }
             currentDirection = currentDirection.turnRight()
         } while (currentDirection != this)
@@ -52,10 +51,36 @@ fun isPositionInTheRoom(player: Pair<Int, Int>, xMax: Int, yMax: Int): Boolean {
     return player.first in 0..xMax && player.second in 0..yMax
 }
 
+fun isLoop(
+    playerLocation: Pair<Int, Int>,
+    playerDirection: Direction,
+    history: List<LocationState>,
+    blocks: MutableSet<Pair<Int, Int>>,
+    potentialBlockLocation: Pair<Int, Int>,
+    xMax: Int,
+    yMax: Int
+): Boolean {
+    var localLocation = playerLocation
+    var localDirection = playerDirection
+    val localHistory = history.toMutableList()
+    val localBlocks = blocks.toMutableSet()
+    localBlocks.add(potentialBlockLocation)
+    while (LocationState(localLocation, localDirection) !in localHistory) {
+        localHistory.add(LocationState(localLocation, localDirection))
+        val (newLocation, newDirection) = localDirection.moveByPartOneRules(localLocation, localBlocks)
+        localLocation = newLocation
+        localDirection = newDirection
+        if (!isPositionInTheRoom(localLocation, xMax, yMax)) {
+            return false
+        }
+    }
+    return true
+}
+
 
 val scanner = Scanner(System.`in`)
 val visited = mutableSetOf<Pair<Int, Int>>()
-val history = mutableListOf<MoveHistory>()
+val history = mutableListOf<LocationState>()
 var playerLocation = Pair(0, 0)
 var playerDirection: Direction = Direction.NORTH
 val blocks = mutableSetOf<Pair<Int, Int>>()
@@ -94,7 +119,7 @@ while (isPositionInTheRoom(playerLocation, xMax, yMax)) {
     if (checkForLoopIfObstacleInFront(playerLocation, playerDirection, history)) {
         potentialBlocks.add(playerDirection.move(playerLocation))
     }
-    history.add(MoveHistory(playerLocation, playerDirection))
+    history.add(LocationState(playerLocation, playerDirection))
     val (newLocation, newDirection) = playerDirection.moveByPartOneRules(playerLocation, blocks)
     playerLocation = newLocation
     playerDirection = newDirection
@@ -106,29 +131,13 @@ println("Potential blocks: ${potentialBlocks.size}")
 fun checkForLoopIfObstacleInFront(
     playerLocation: Pair<Int, Int>,
     playerDirection: Direction,
-    history: MutableList<MoveHistory>
+    history: MutableList<LocationState>
 ): Boolean {
-    val potentialBlockLocation = playerDirection.move(playerLocation)
-    val nextMove = playerDirection.moveByPartOneRules(playerLocation, blocks)
+    val potentialBlockLocation = playerDirection.moveByPartOneRules(playerLocation, blocks).location
     val alreadyVisited = potentialBlockLocation in visited
-    val pathAlreadyBlocked = potentialBlockLocation != nextMove.newLocation
     val positionNotInTheRoom = !isPositionInTheRoom(potentialBlockLocation, xMax, yMax)
-    if (alreadyVisited || pathAlreadyBlocked || positionNotInTheRoom) {
+    if (alreadyVisited || positionNotInTheRoom) {
         return false
     }
-    var localLocation = playerLocation
-    var localDirection = playerDirection
-    val localHistory = history.toMutableList()
-    val localBlocks = blocks.toMutableSet()
-    localBlocks.add(potentialBlockLocation)
-    while (MoveHistory(localLocation, localDirection) !in localHistory) {
-        localHistory.add(MoveHistory(localLocation, localDirection))
-        val (newLocation, newDirection) = localDirection.moveByPartOneRules(localLocation, localBlocks)
-        localLocation = newLocation
-        localDirection = newDirection
-        if (!isPositionInTheRoom(localLocation, xMax, yMax)) {
-            return false
-        }
-    }
-    return true;
+    return isLoop(playerLocation, playerDirection, history, blocks, potentialBlockLocation, xMax, yMax)
 }

day06.kts.testvalue

@@ -0,0 +1,2 @@
+Player location: 4883
+Potential blocks: 1655