Prepare for other years

2020-12-30 18:01:52 +01:00
parent 522618d106
commit 4a90257257
81 changed files with 277 additions and 253 deletions
@@ -0,0 +1,77 @@
+package be.vandewalleh.aoc.days
+
+import be.vandewalleh.aoc.utils.input.Day
+import be.vandewalleh.aoc.utils.input.Groups
+import be.vandewalleh.aoc.utils.input.Input
+
+private data class PlayedGame(val a: List<Int>, val b: List<Int>)
+
+@Day(22)
+class Day22(@Groups val input: Input<List<List<String>>>) {
+    private val one = input.value[0].drop(1).map { it.toInt() }
+    private val two = input.value[1].drop(1).map { it.toInt() }
+
+    fun part1(): Long {
+        val oneDeque = ArrayDeque(one)
+        val twoDeque = ArrayDeque(two)
+
+        while (oneDeque.isNotEmpty() && twoDeque.isNotEmpty()) {
+            val a = oneDeque.removeFirst()
+            val b = twoDeque.removeFirst()
+
+            if (a > b) {
+                oneDeque.addLast(a)
+                oneDeque.addLast(b)
+            } else {
+                twoDeque.addLast(b)
+                twoDeque.addLast(a)
+            }
+        }
+
+        val deque = if (oneDeque.isEmpty()) twoDeque else oneDeque
+        return deque.score()
+    }
+
+    private fun ArrayDeque<Int>.score() =
+        asReversed().mapIndexed { index, value -> (index + 1).toLong() * value.toLong() }.sum()
+
+    fun part2(): Long {
+        val oneDeque = ArrayDeque(one)
+        val twoDeque = ArrayDeque(two)
+
+        val winner = playGame(oneDeque, twoDeque)
+        val deque = if (winner == 1) oneDeque else twoDeque
+        return deque.score()
+    }
+
+    private fun playGame(one: ArrayDeque<Int>, two: ArrayDeque<Int>): Int {
+        val playedGames = mutableSetOf<PlayedGame>()
+
+        while (one.isNotEmpty() && two.isNotEmpty()) {
+            if (!playedGames.add(PlayedGame(one.toList(), two.toList()))) return 1
+
+            val a = one.removeFirst()
+            val b = two.removeFirst()
+
+            val winner = when {
+                one.size >= a && two.size >= b -> playGame(
+                    ArrayDeque(one.take(a)),
+                    ArrayDeque(two.take(b))
+                )
+                a > b -> 1
+                else -> 2
+            }
+
+            if (winner == 1) {
+                one.addLast(a)
+                one.addLast(b)
+            } else {
+                two.addLast(b)
+                two.addLast(a)
+            }
+
+        }
+
+        return if (one.isEmpty()) 2 else 1
+    }
+}