AOC - Day 23

Author: cortinico

src/main/java/Exercise23-part2.kt

@@ -0,0 +1,49 @@
+fun main() {
+ val input = object {}.javaClass.getResource("input-23.txt").readText()
+ .toCharArray()
+ .map(Character::getNumericValue)
+
+ val size = 1_000_000
+ val cups = Array(size + 1) { Cup(it) }
+
+ cups.onEachIndexed { index, cup ->
+ if (index == cups.size - 1) {
+ cup.next = cups[1]
+ } else {
+ cup.next = cups[index + 1]
+ }
+ }
+
+ input.forEachIndexed { index, elem ->
+ if (index != input.size - 1) {
+ cups[elem].next = cups[input[index + 1]]
+ } else {
+ cups[elem].next = cups[input.size + 1]
+ }
+ }
+
+ var current = cups[input.first()]
+ cups.last().next = current
+
+ repeat(10_000_000) {
+ val curr1 = current.next
+ val curr2 = curr1.next
+ val curr3 = curr2.next
+ val currAfter = curr3.next
+
+ var toFind = current.num - 1
+
+ while (toFind == curr1.num || toFind == curr2.num || toFind == curr3.num) toFind--
+ if (toFind == 0) {
+ toFind = size
+ while (toFind == curr1.num || toFind == curr2.num || toFind == curr3.num) toFind--
+ }
+ val dest0 = cups[toFind]
+ val dest1 = dest0.next
+ dest0.next = curr1
+ curr3.next = dest1
+ current.next = currAfter
+ current = currAfter
+ }
+ println((cups[1].next.num).toLong() * (cups[1].next.next.num).toLong())
+}

src/main/java/Exercise23.kt

@@ -0,0 +1,55 @@
+fun main() {
+ val input = object {}.javaClass.getResource("input-23.txt").readText()
+ .toCharArray()
+ .map(Character::getNumericValue)
+
+ val size = input.size
+ val cups = Array(size + 1) { Cup(it) }
+
+ cups.onEachIndexed { index, cup ->
+ if (index == cups.size - 1) {
+ cup.next = cups[1]
+ } else {
+ cup.next = cups[index + 1]
+ }
+ }
+
+ input.forEachIndexed { index, elem ->
+ if (index != input.size - 1) {
+ cups[elem].next = cups[input[index + 1]]
+ } else {
+ cups[elem].next = cups[input.first()]
+ }
+ }
+
+ var current = cups[input.first()]
+ repeat(100) {
+ val curr1 = current.next
+ val curr2 = curr1.next
+ val curr3 = curr2.next
+ val currAfter = curr3.next
+
+ var toFind = current.num - 1
+
+ while (toFind == curr1.num || toFind == curr2.num || toFind == curr3.num) toFind--
+ if (toFind == 0) {
+ toFind = size
+ while (toFind == curr1.num || toFind == curr2.num || toFind == curr3.num) toFind--
+ }
+ val dest0 = cups[toFind]
+ val dest1 = dest0.next
+ dest0.next = curr1
+ curr3.next = dest1
+ current.next = currAfter
+ current = currAfter
+ }
+ var t = cups[1]
+ (1 until size).fold("") { acc, _ ->
+ t = t.next
+ "$acc${t.num}"
+ }.also(::println)
+}
+
+class Cup(val num: Int) {
+ lateinit var next: Cup
+}

src/main/resources/input-23.txt

@@ -0,0 +1 @@
+123487596