Day 5 Part 1

2024/src/main/kotlin/day5.kt

@@ -0,0 +1,38 @@
+fun main() {
+
+    val rules = mutableListOf<Pair<Int, Int>>()
+    var completedRules = false
+
+    var part1 = 0
+
+    for (line in readInput("day5.txt")) {
+        if (completedRules) {
+            val job = line.split(",").map { it.toInt() }
+            assert(job.count() % 2 != 0)
+            val middlePage = job[job.count() / 2]
+
+            var matches = true
+            for ((first, second) in rules) {
+                val firstIndex = job.indexOf(first)
+                val secondIndex = job.indexOf(second)
+
+                if (firstIndex != -1 && secondIndex != -1 && firstIndex > secondIndex) {
+                    matches = false
+                    break
+                }
+            }
+
+            if (matches) {
+                part1 += middlePage
+            }
+        } else if (line.isEmpty()) {
+            completedRules = true
+        } else {
+            val (first, second) = line.split("|", limit = 2).map { it.toInt() }
+            rules.add(first to second)
+        }
+    }
+
+    println("Part 1: $part1")
+
+}

2024/src/main/resources/day5-sample.txt

@@ -0,0 +1,28 @@
+47|53
+97|13
+97|61
+97|47
+75|29
+61|13
+75|53
+29|13
+97|29
+53|29
+61|53
+97|53
+61|29
+47|13
+75|47
+97|75
+47|61
+75|61
+47|29
+75|13
+53|13
+
+75,47,61,53,29
+97,61,53,29,13
+75,29,13
+75,97,47,61,53
+61,13,29
+97,13,75,29,47