Day 5.

day05.kts

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+#!/usr/bin/env kotlin
+import java.io.File
+import java.util.Scanner
+
+var orderingRules = mutableListOf<Pair<Int, Int>>()
+var pagesList = mutableListOf<MutableList<Int>>()
+val scanner = Scanner(File("day05input.txt"))
+while (scanner.hasNextLine()) {
+    val line = scanner.nextLine()
+    if (line.contains('|')) {
+        val order = line.split("|").map { it.toInt() }
+        orderingRules.add(Pair(order[0], order[1]))
+    } else if (line.contains(',')) {
+        val pages = line.split(",").map { it.toInt() }
+        pagesList.add(pages.toMutableList())
+    }
+}
+var orderedMiddleSum = 0
+var unorderedMiddleSum = 0
+for (page in pagesList) {
+    if (isOrdered(page)) {
+        orderedMiddleSum += page[page.size / 2]
+    } else {
+        val orderedPage = page.sortedWith(Comparator { a, b -> compareByRules(a, b) })
+        unorderedMiddleSum += orderedPage[orderedPage.size / 2]
+    }
+}
+
+fun compareByRules(a: Int, b: Int): Int {
+    for ((smaller, bigger) in orderingRules) {
+        if (a == smaller && b == bigger) return -1
+        if (a == bigger && b == smaller) return 1
+    }
+    return 0
+}
+
+fun isOrdered(page: MutableList<Int>): Boolean {
+    for (i in orderingRules.indices) {
+        val (smaller, bigger) = orderingRules[i]
+        val smallerIndex = page.indexOf(smaller)
+        val biggerIndex = page.indexOf(bigger)
+        if (smallerIndex != -1 && biggerIndex != -1 && biggerIndex < smallerIndex) {
+            return false
+        }
+    }
+    return true
+}
+
+println("Ordered middle sum: $orderedMiddleSum")
+println("Unordered middle sum: $unorderedMiddleSum")

day05.kts.testvalue

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+Ordered middle sum: 5713
+Unordered middle sum: 5180