wip

Author: spaenleh

Sources/Day04.swift

@@ -1,14 +1,14 @@
 import Algorithms
 
-func searchInNeighbors(pos: Coord, _ grid: Grid) -> [Coord] {
-  pos.fullNeighbors.included(in: grid).filter { n in
+func searchInNeighbors(pos: Coord, _ grid: Grid<Character>) -> [Coord] {
+  grid.filter(allInside: pos.fullNeighbors).filter { n in
     grid[n] == "M"
   }
 }
 
-func isMAS(pos: Coord, _ grid: Grid) -> Bool {
+func isMAS(pos: Coord, _ grid: Grid<Character>) -> Bool {
   let candidates = pos.cornerNeighbors
-  if (candidates.allSatisfy { $0.isInside(grid: grid) }) {
+  if grid.filter(allInside: candidates).count == 4 {
     let l = candidates.map { grid[$0] }.compactMap { $0 }
     let letterSet = Set(l)
     // same letter can not be on opposite side
@@ -17,7 +17,7 @@ func isMAS(pos: Coord, _ grid: Grid) -> Bool {
   return false
 }
 
-func isWhole(pos: Coord, inDir: Coord, grid: Grid) -> Bool {
+func isWhole(pos: Coord, inDir: Coord, grid: Grid<Character>) -> Bool {
   let aPos = pos + inDir
   let sPos = aPos + inDir
   if let aValue = grid[aPos], let sValue = grid[sPos] {
@@ -27,12 +27,12 @@ func isWhole(pos: Coord, inDir: Coord, grid: Grid) -> Bool {
 }
 
 struct Day04: AdventDay {
-  var grid: Grid
+  var grid: Grid<Character>
   init(data: String) {
     grid = Grid(from: data)
   }
 
-  func countAllWhere(letter search: Character, predicate: (Coord, Grid) -> Bool) -> Int {
+  func countAllWhere(letter search: Character, predicate: (Coord, Grid<Character>) -> Bool) -> Int {
     grid.raw.enumerated().map { (y, line) in
       line.enumerated().map { (x, letter) in
         if letter == search {

Sources/Day06.swift

@@ -28,7 +28,7 @@ struct Guard {
 }
 
 struct Day06: AdventDay {
-  var grid: Grid
+  var grid: Grid<Character>
   init(data: String) {
     grid = Grid(from: data)
   }
@@ -38,7 +38,7 @@ struct Day06: AdventDay {
     var steps: [Coord] = [Coord]()
     var obstacles: [Coord] = [Coord]()
     var officer = Guard(pos: grid.firstCoord(of: "^")!, direction: .North)
-    while officer.pos.isInside(grid: grid) {
+    while grid.includes(coord: officer.pos) {
       // save position
       locations.insert(officer.pos)
 
@@ -64,7 +64,7 @@ struct Day06: AdventDay {
   func doesComeBack(step: Coord) -> Bool {
     var officer = Guard(pos: grid.firstCoord(of: "^")!, direction: .North)
     var locations: [Coord] = [Coord]()
-    while officer.pos.isInside(grid: grid) {
+    while grid.includes(coord: officer.pos) {
       locations.append(officer.pos)
 
       // move the guard

Sources/Day10.swift

@@ -1,7 +1,7 @@
 import Algorithms
 
 struct Day10: AdventDay {
-  var grid: Grid
+  var grid: Grid<Character>
 
   init(data: String) {
     grid = Grid(from: data)

Sources/Day12.swift

@@ -0,0 +1,91 @@
+import Algorithms
+
+struct Field {
+  var id: Character
+  var area: Int = 1
+  var perimeter: Int = 0
+  var coords: [Coord] = [Coord]()
+
+  func compute() -> Int {
+    area * perimeter
+  }
+
+  mutating func visited(coord: Coord) {
+    coords.append(coord)
+  }
+}
+extension Field {
+  init(id: Character) {
+    self.id = id
+    area = 1
+    perimeter = 0
+  }
+}
+
+struct Day12: AdventDay {
+  var grid: Grid<Character>
+
+  init(data: String) {
+    grid = Grid(from: data)
+  }
+
+  func exploreField(from pos: Coord, id: Character, field oldField: Field) -> Field {
+    var field = oldField
+    field.visited(coord: pos)
+    field.area += 1
+    // explore the grid
+    for neighbor in pos.crossNeighbors {
+      print("checking for", neighbor)
+      if let candidate = grid[neighbor] {
+        if candidate == id {
+          print("we are together")
+          // same value means we have a new area tile
+          return exploreField(from: neighbor, id: id, field: field)
+        } else {
+          print("someone else")
+          // this is a frontier
+          field.perimeter += 1
+        }
+      } else {
+        print("grid boundary")
+        // this is the frontier of the grid
+        field.perimeter += 1
+      }
+    }
+    return field
+  }
+
+  func part1() -> Int {
+
+    var record = [Coord: Bool]()
+    var fields = [Field]()
+    for y in 0..<grid.height {
+      for x in 0..<grid.width {
+        let currentPos = Coord(x: x, y: y)
+        print(currentPos)
+        // position has already been visited
+        guard record[currentPos] == nil else {
+          print("already visited")
+          continue
+        }
+
+        if let gridValue = grid[currentPos] {
+          // start a new field
+          print("starting a new field")
+          let field = exploreField(
+            from: currentPos, id: gridValue, field: Field(id: gridValue))
+          fields.append(field)
+          field.coords.forEach { s in
+            record[s] = true
+          }
+          print("-------", field)
+        }
+      }
+    }
+    return fields.map { $0.compute() }.sum
+  }
+
+  func part2() -> Int {
+    0
+  }
+}

Sources/Helpers/Coord.swift

@@ -36,11 +36,6 @@ struct Coord {
   var fullNeighbors: [Coord] {
     self.cornerNeighbors + self.crossNeighbors
   }
-
-  func isInside(grid: Grid) -> Bool {
-    self.x >= 0 && self.x <= grid.width - 1 && self.y >= 0 && self.y <= grid.height - 1
-  }
-
 }
 
 extension Coord: Equatable {}
@@ -89,9 +84,3 @@ extension Coord {
     return Self(x: lhs.x * rhs, y: lhs.y * rhs)
   }
 }
-
-extension Array where Array.Element == Coord {
-  func included(in grid: Grid) -> Self {
-    self.filter { $0.isInside(grid: grid) }
-  }
-}

Sources/Helpers/Grid.swift

@@ -1,6 +1,4 @@
-struct Grid {
-  typealias Element = Character
-
+struct Grid<Element: Sendable> {
   var raw: [[Element]]
 
   // dimensions
@@ -12,7 +10,7 @@ struct Grid {
   }
 
   subscript(_ coord: Coord) -> Element? {
-    if coord.isInside(grid: self) {
+    if self.includes(coord: coord) {
       return raw[coord.y][coord.x]
     }
     return nil
@@ -21,9 +19,21 @@ struct Grid {
   subscript(col: Int, row: Int) -> Element {
     raw[row][col]
   }
+
+  func includes(coord: Coord) -> Bool {
+    coord.x >= 0 && coord.x <= self.width - 1 && coord.y >= 0 && coord.y <= self.height - 1
+  }
+
+  func filter(allInside: [Coord]) -> [Coord] {
+    allInside.filter { self.includes(coord: $0) }
+  }
 }
 
-extension Grid {
+extension Grid: Sendable {
+
+}
+
+extension Grid where Element == Character {
   /// creates a Grid of characters from a multiline string
   init(from data: String) {
     self.raw = data.lines().map { Array($0) }
@@ -36,11 +46,7 @@ extension Grid {
       }.joined(by: "\n"))
   }
 
-  func includes(coord: Coord) -> Bool {
-    coord.x >= 0 && coord.x <= self.width - 1 && coord.y >= 0 && coord.y <= self.height - 1
-  }
-
-  func firstCoord(of char: Character) -> Coord? {
+  func firstCoord(of char: Element) -> Coord? {
     let index = self.raw.flatMap { $0 }.firstIndex(of: char)
     if let index = index {
       let x = index % self.width

Tests/Day12.swift

@@ -0,0 +1,31 @@
+import Testing
+
+@testable import aoc
+
+@Suite("Day12")
+struct Day12Tests {
+  let testData = """
+    RRRRIICCFF
+    RRRRIICCCF
+    VVRRRCCFFF
+    VVRCCCJFFF
+    VVVVCJJCFE
+    VVIVCCJJEE
+    VVIIICJJEE
+    MIIIIIJJEE
+    MIIISIJEEE
+    MMMISSJEEE
+    """
+
+  @Test("part1")
+  func testPart1() async throws {
+    let challenge = Day12(data: testData)
+    #expect(challenge.part1() == 1930)
+  }
+
+  @Test("part2")
+  func testPart2() async throws {
+    let challenge = Day12(data: testData)
+    #expect(challenge.part2() == 0)
+  }
+}