<?xml version="1.0" encoding="UTF-8"?>

<module type="JAVA_MODULE" version="4">

<component name="NewModuleRootManager" inherit-compiler-output="true">

<exclude-output />

<content url="file://$MODULE_DIR$">

<sourceFolder url="file://$MODULE_DIR$/resources" type="java-resource" />

<sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />

<sourceFolder url="file://$MODULE_DIR$/test" isTestSource="true" />

<sourceFolder url="file://$MODULE_DIR$/testResources" type="java-test-resource" />

</content>

<orderEntry type="inheritedJdk" />

<orderEntry type="sourceFolder" forTests="false" />

<orderEntry type="library" name="KotlinJavaRuntime" level="project" />

</component>

</module>

import java.io.File

import java.util.*

import kotlin.collections.ArrayList

fun main(args: Array<String>) {

println("AOC 2023, Day 8, Part 2 starting!!!!")

var firstLine = false

var directions = "None"

val allNodes = ArrayList<Node>()

File(args[0]).forEachLine {

if(!firstLine) {

directions = it

firstLine = true

} else if(it.isNotEmpty()) {

val nodeName = it.substring(0..2)

val connectionLeft = it.substring(7..9)

val connectionRight = it.substring(12..14)

allNodes.add(Node(nodeName, connectionLeft, connectionRight))

}

}

println("Total Nodes: ${allNodes.count()}")

val nodesEndWithA = findNodesEndsWithA(allNodes)

println("Finding nodes that end with A: $nodesEndWithA")

val nodesEndWithZ = findNodesEndsWithZ(allNodes)

println("Finding nodes that end with Z: $nodesEndWithZ")

val foundCount = Stack<Long>()

nodesEndWithA.forEach {

println("Starting search starting with $it")

foundCount.push(traverseNodeIterative(directions, allNodes, it))

println("found it! Path took ${foundCount.peek()} steps.")

}

println("Final path count results: $foundCount")

var stepsStack = foundCount.pop()

while(!foundCount.empty()) {

stepsStack = lcm(stepsStack, foundCount.pop())

}

println("Steps taken to traverse to all nodes end with Z: $stepsStack")

println("AOC 2023, Day 8, Part 2 completed!!!")

}

fun lcm(a: Long, b: Long): Long {

return (a / gcd(a, b)) * b

}

fun gcd(a: Long, b: Long): Long {

if (a == 0L) return b

return gcd(b % a, a)

}

fun findNodesEndsWithA(nodes: ArrayList<Node>):ArrayList<Node> {

val nodesEndsWithA = ArrayList<Node>()

nodes.filter { it.nodeName.last() == 'A' }.toCollection(nodesEndsWithA)

return nodesEndsWithA

}

fun findNodesEndsWithZ(nodes: ArrayList<Node>):ArrayList<Node> {

val nodesEndsWithZ = ArrayList<Node>()

nodes.filter { it.nodeName.last() == 'Z' }.toCollection(nodesEndsWithZ)

return nodesEndsWithZ

}

fun traverseNodeIterative(directions: String, nodes: ArrayList<Node>, startNode: Node): Long {

var totalSteps = 0L

var nextStep = 0

var currentNode = Node(startNode.nodeName, startNode.connectionLeft, startNode.connectionRight)

var nextNode:Node

while(currentNode.nodeName.last() != 'Z') {

val leftOrRight = directions[nextStep]

nextNode = if(leftOrRight.compareTo('L') == 0) {

nodes.find { it.nodeName == currentNode.connectionLeft }!!

} else {

nodes.find { it.nodeName == currentNode.connectionRight }!!

}

currentNode = nextNode

nextStep++

totalSteps++

if(nextStep >= directions.length) {

nextStep = 0

}

}

return totalSteps

}

data class Node (val nodeName:String, val connectionLeft:String, val connectionRight:String)