day3

Author: spaenleh

README.md

@@ -10,7 +10,7 @@ Below is my current advancement in Advent of code:
 |:---|:---:|:---:|
 | Day 1 | :star: | :star: |
 | Day 2 | :star: | :star: |
-| Day 3 |  |  |
+| Day 3 | :star: | :star: |
 | Day 4 |  |  |
 | Day 5 |  |  |
 | Day 6 |  |  |

Sources/Day03.swift

@@ -3,23 +3,33 @@ import Algorithms
 struct Day03: AdventDay {
   var data: String
 
-  func part1() -> Int {
-    let search = /mul\((\d+),(\d+)\)/
-
-    return data.ranges(of: search).map { match in
-      let string = data[match].trimmingPrefix("mul(").trimmingCharacters(in: .punctuationCharacters)
-      let numbers = string.split(
-        separator: ","
-      )
-      return numbers.map {
-        Int($0)
-      }.compactMap {
-        $0
-      }.reduce(1, *)
+  /// computes the operations from a corrupter memory dump
+  func compute(data input: String) -> Int {
+    input.ranges(of: /mul\(\d+,\d+\)/).map { match in
+      input[match].trimmingPrefix("mul(").trimmingCharacters(in: .punctuationCharacters)
+        .split(
+          separator: ","
+        )
+        .map {
+          Int($0)
+        }.compactMap {
+          $0
+        }.reduce(1, *)
     }.sum
   }
 
+  func part1() -> Int {
+    compute(data: data)
+  }
+
   func part2() -> Int {
-    0
+    let singleLine = data.replacingOccurrences(of: "\n", with: "")
+
+    /// remove anything that is between a "don't()" and a "do()"
+    /// be careful to match as few characters as possible with `.*?`
+    let newData = singleLine.replacing(
+      /(don't\(\).*?do\(\))/, with: "")
+
+    return compute(data: newData)
   }
 }

Sources/Extensions/String+Parsing.swift

@@ -6,6 +6,10 @@ extension StringProtocol {
     self.trimmingCharacters(in: .whitespacesAndNewlines)
   }
 
+  func concatLines() -> String {
+    self.replacingOccurrences(of: "\n", with: "")
+  }
+
   func lines() -> [SubSequence] {
     self.split(separator: "\n")
   }

Tests/Day03.swift

@@ -16,7 +16,20 @@ struct Day03Tests {
 
   @Test("part2")
   func testPart2() async throws {
-    let challenge = Day03(data: testData)
-    #expect(challenge.part2() == 0)
+    let challenge = Day03(
+      data: """
+        xmul(2,4)&mul[3,7]!^don't()_mul(5,5)+mul(32,64](mul(11,8)uno()?mul(8,5))
+        xmul(2,4)&mul[3,7]!^don't()_mul(5,5)+mul(32,64](mul(11,8)undo()?mul(8,5))
+        """)
+    #expect(challenge.part2() == 48)
+  }
+
+  @Test("edges")
+  func testEdges() async throws {
+    let challenge = Day03(
+      data: """
+        don't()ado()_mul(5,5)do()mul(8,5)
+        """)
+    #expect(challenge.part2() == 25 + (8 * 5))
   }
 }

Tests/Extensions/String+Parsing.swift

@@ -10,6 +10,11 @@ struct StringExtensions {
     #expect("\n\nhello\n".trimmed() == "hello")
   }
 
+  @Test("Concatenate Lines")
+  func testConcatLines() async throws {
+    #expect("h\ne\nl\nl\no".concatLines() == "hello")
+  }
+
   @Test("Lines Parsing")
   func testLinesParsing() async throws {
     #expect("".lines() == [])