Day05

Author: ath0s

src/main/kotlin/Day05.kt

@@ -0,0 +1,61 @@
+import java.nio.file.Path
+import kotlin.io.path.readLines
+import kotlin.math.max
+import kotlin.math.min
+
+
+class Day05 : Day {
+    override fun partOne(filename: String, verbose: Boolean): Int {
+        val (freshRanges, ingredients) = filename.asPath().parseInventory()
+
+        return ingredients.count { ingredient ->
+            freshRanges.any { ingredient in it }
+        }
+    }
+
+    override fun partTwo(filename: String, verbose: Boolean): Long {
+        val (freshRanges, _) = filename.asPath().parseInventory()
+        val sortedRanges = freshRanges.sortedBy { it.last }
+        val merged = mergeOverlap(sortedRanges)
+        return merged.sumOf { it.last - it.first + 1 }
+    }
+
+    private fun Path.parseInventory(): Pair<List<LongRange>, List<Long>> {
+        var freshRangesDone = false
+
+        val freshRanges = mutableListOf<LongRange>()
+        val ingredients = mutableListOf<Long>()
+        readLines().forEach { line ->
+            when {
+                line.isBlank() -> freshRangesDone = true
+                freshRangesDone -> ingredients += line.toLong()
+                else -> {
+                    val (start, stop) = line.split("-")
+                    freshRanges += start.toLong()..stop.toLong()
+                }
+            }
+        }
+        return freshRanges to ingredients
+    }
+
+    private fun mergeOverlap(ranges: List<LongRange>): List<LongRange> {
+        val merged = mutableListOf<LongRange>()
+        var current = ranges.first()
+        for (i in 1..<ranges.size) {
+            val range = ranges[i]
+            if (current.first <= range.last && range.first <= current.last) {
+                current = min(current.first, range.first)..max(current.last, range.last)
+            } else {
+                merged += current
+                current = range
+            }
+        }
+        merged += current
+        return merged
+    }
+
+    companion object : Day.Main("Day05.txt") {
+        @JvmStatic
+        fun main(args: Array<String>) = main()
+    }
+}