Day 3

Sources/AdventOfCode2024/AdventOfCode2024.swift

@@ -4,6 +4,7 @@ public struct AdventOfCode2024: Year {
     public let days: [any Day] = [
         Day1(),
         Day2(),
+        Day3(),
         // {DAYS}
     ]
 

Sources/AdventOfCode2024/Day3/Day3.swift

@@ -0,0 +1,50 @@
+import Algorithms
+import Foundation
+import Utilities
+import RegexBuilder
+
+public struct Day3: Day {
+    let mulRegex = Regex {
+        "mul("
+        Capture {
+            OneOrMore(.digit)
+        } transform: { Int($0)! }
+        ","
+        Capture {
+            OneOrMore(.digit)
+        } transform: { Int($0)! }
+        ")"
+    }
+
+    public func part1Solution(for input: Input) -> Int {
+        var total = 0
+        for match in input.raw.matches(of: mulRegex) {
+            total += match.1 * match.2
+        }
+        return total
+    }
+
+    public func part2Solution(for input: Input) -> Int {
+        let regex = Regex {
+            ChoiceOf {
+                mulRegex
+                "don't()"
+                "do()"
+            }
+        }
+
+        var enabled = true
+
+        var total = 0
+        for match in input.raw.matches(of: regex) {
+            if match.0 == "do()" {
+                enabled = true
+            } else if match.0 == "don't()" {
+                enabled = false
+            } else if enabled {
+                total += match.1! * match.2!
+            }
+        }
+        return total
+    }
+}