🖥 See why their computers are having issues again

Author: scorphus

src/aoc24.gleam

@@ -3,11 +3,13 @@ import gleam/io
 
 import day01
 import day02
+import day03
 
 pub fn main() {
   case argv.load().arguments {
     ["1"] -> day01.main()
     ["2"] -> day02.main()
+    ["3"] -> day03.main()
     _ -> io.println("No day specified. Usage: aoc24 <day>")
   }
 }

src/day03.gleam

@@ -0,0 +1,50 @@
+import gleam/int
+import gleam/io
+import gleam/list
+import gleam/string
+
+import shared
+
+pub fn main() {
+  let memory =
+    shared.read_input([])
+    |> string.join("")
+  io.println("Part 1: " <> int.to_string(part_1(memory)))
+  io.println("Part 2: " <> int.to_string(part_2(memory)))
+}
+
+fn part_1(memory: String) -> Int {
+  memory
+  |> string.split("mul(")
+  |> list.fold([], fn(acc, operands) {
+    list.flatten([acc, string.split(operands, ")")])
+  })
+  |> list.map(mul)
+  |> list.fold(0, fn(acc, value) { acc + value })
+}
+
+fn mul(operands: String) -> Int {
+  operands
+  |> string.split(",")
+  |> list.map(int.parse)
+  |> list.fold(1, fn(acc, operand) {
+    case operand {
+      Ok(value) -> acc * value
+      Error(_) -> 0
+    }
+  })
+}
+
+fn part_2(memory: String) -> Int {
+  memory
+  |> string.split("do()")
+  |> list.fold([], fn(acc, expressions) {
+    case string.split(expressions, "don't()") {
+      [] -> acc
+      ["", ..] -> acc
+      [expressions, ..] -> list.flatten([acc, [expressions]])
+    }
+  })
+  |> string.join("")
+  |> part_1()
+}

src/shared.gleam

@@ -1,5 +1,6 @@
 import gleam/erlang
 import gleam/int
+import gleam/list
 import gleam/string
 
 pub fn read_input(lines: List(String)) -> List(String) {
@@ -10,7 +11,7 @@ pub fn read_input(lines: List(String)) -> List(String) {
       [line, ..lines]
       |> read_input()
     }
-    Error(_) -> lines
+    Error(_) -> list.reverse(lines)
   }
 }