Day 07

src/day07.scala

@@ -0,0 +1,44 @@
+package aoc
+package day07
+
+val dayNumber = "07"
+
+@main def part1: Unit =
+  println(part1(loadInput(dayNumber)))
+
+@main def part2: Unit =
+  println(part2(loadInput(dayNumber)))
+
+def part1(input: String): String =
+  val ops: List[(Long, Long) => Long] = List(_ * _, _ + _)
+  parseInput(input)
+    .collect { case (res, nums) if isSolvable(res, nums, ops) => res }
+    .sum
+    .toString
+
+def part2(input: String): String =
+  val ops: List[(Long, Long) => Long] =
+    List(_ * _, _ + _, (a, b) => s"$a$b".toLong)
+  parseInput(input)
+    .collect { case (res, nums) if isSolvable(res, nums, ops) => res }
+    .sum
+    .toString
+
+def parseInput(input: String) =
+  input
+    .split("\n")
+    .toList
+    .map { case s"$res: $nums" =>
+      (res.toLong, nums.split(" ").map(_.toLong).toList)
+    }
+
+def isSolvable(
+    res: Long,
+    nums: List[Long],
+    ops: List[(Long, Long) => Long]
+): Boolean =
+  nums.tail
+    .foldLeft(List(nums.head))((acc, num) =>
+      acc.flatMap(total => ops.map(_(total, num)))
+    )
+    .contains(res)