Readability improvements

day14/d14p2.swift

@@ -55,7 +55,9 @@ func printRobots(_ bots: [Robot]) -> String {
             screen[q][bot.x] = "█"
         }
     }
-    return screen.map { row in row.joined() }.joined(separator: "\n")
+    return "┌" + String(repeating: "─", count: w) + "┐\n" +
+        screen.map { row in "│" + row.joined() + "│" }.joined(separator: "\n") +
+        "\n└" + String(repeating: "─", count: w) + "┘"
 }
 
 var bots = try readInput(CommandLine.arguments[1])

day15/d15p2.swift

@@ -16,9 +16,9 @@ enum Move: Character, CustomStringConvertible {
     }
 }
 
-struct Item: Hashable, CustomStringConvertible {
+struct Item: Hashable {
     let (x, y): (Int, Int)
-    var description: String { return "(\(x), \(y))" }
+    var rightCell: Item { return Item(x: x+1, y: y) }
     var gps: Int { return x + 100*y }
     func move(_ m: Move) -> Item {
         let (dx, dy) = m.delta
@@ -58,10 +58,11 @@ struct Map: CustomStringConvertible {
         for (y, line) in s.enumerated() {
             for (x0, char) in line.enumerated() {
                 let x = 2*x0
+                let item = Item(x: x, y: y)
                 switch char {
-                case "#": walls.formUnion([Item(x: x, y: y), Item(x: x+1, y: y)])
+                case "#": walls.formUnion([item, item.rightCell])
-                case "O": boxes.boxes.insert(Item(x: x, y: y))
+                case "O": boxes.boxes.insert(item)
-                case "@": bot = Item(x: x, y: y)
+                case "@": bot = item
                 default: ()
                 }
             }
@@ -70,19 +71,19 @@ struct Map: CustomStringConvertible {
     }
 
     mutating func move(_ dir: Move) {
-        var pushes: Set<Item> = []
+        var boxesToPush: Set<Item> = []
-        var nexts: Set<Item> = [bot.move(dir)]
+        var dests: Set<Item> = [bot.move(dir)]
-        while !nexts.isEmpty {
+        while !dests.isEmpty {
-            let next = nexts.removeFirst()
+            let next = dests.removeFirst()
             if let box = boxes.at(x: next.x, y: next.y) {
-                pushes.insert(box)
+                boxesToPush.insert(box)
                 let movedBox = box.move(dir)
                 switch dir {
-                case Move.w: nexts.insert(movedBox)
+                case Move.w: dests.insert(movedBox)
-                case Move.e: nexts.insert(Item(x: movedBox.x+1, y: movedBox.y))
+                case Move.e: dests.insert(movedBox.rightCell)
                 case Move.n, Move.s:
-                    nexts.insert(movedBox)
+                    dests.insert(movedBox)
-                    nexts.insert(Item(x: movedBox.x+1, y: movedBox.y))
+                    dests.insert(movedBox.rightCell)
                 }
                 continue
             }
@@ -90,8 +91,8 @@ struct Map: CustomStringConvertible {
                 return
             }
         }
-        pushes.forEach { boxes.boxes.remove($0) }
+        boxesToPush.forEach { boxes.boxes.remove($0) }
-        pushes.forEach { boxes.boxes.insert($0.move(dir)) }
+        boxesToPush.forEach { boxes.boxes.insert($0.move(dir)) }
         bot = bot.move(dir)
     }
 }