day 18, part 1 (improved in preparation to part 2)

day18-easy/src/main.zig

@@ -104,14 +104,59 @@ fn readNumber(comptime T: type, line: []const u8, index: *usize) T {
     return if (is_negative) (0 - result) else result;
 }
 
-fn GenericTerrain(comptime CoordinateType: type, comptime height: CoordinateType, comptime width: CoordinateType, comptime CellType: type) type {
+fn Coordinates(comptime CoordinateType: type) type {
     return struct {
         const Self = @This();
         x: CoordinateType,
         y: CoordinateType,
+
+        fn isSameX(self: *const Self, other: Self) bool {
+            return self.x == other.x;
+        }
+
+        fn approachX(self: *Self, other: Self) void {
+            if (self.x < other.x) {
+                self.x += 1;
+            } else {
+                self.x -= 1;
+            }
+        }
+
+        fn isSameY(self: *const Self, other: Self) bool {
+            return self.y == other.y;
+        }
+
+        fn approachY(self: *Self, other: Self) void {
+            if (self.y < other.y) {
+                self.y += 1;
+            } else {
+                self.y -= 1;
+            }
+        }
+    };
+}
+
+fn GenericTerrain(comptime CoordinateType: type, comptime height: CoordinateType, comptime width: CoordinateType, comptime CellType: type) type {
+    return struct {
+        const Self = @This();
+        coordinates: Coordinates(CoordinateType),
         cells: [height][width]CellType,
         fn initZeroes() Self {
-            return .{ .x = height / 2, .y = width / 2, .cells = std.mem.zeroes([height][width]CellType) };
+            return .{
+                .coordinates = .{
+                    .x = height / 2,
+                    .y = width / 2,
+                },
+                .cells = std.mem.zeroes([height][width]CellType),
+            };
+        }
+
+        fn getCurrentCell(self: *const Self) CellType {
+            return self.cells[self.coordinates.x][self.coordinates.y];
+        }
+
+        fn setCurrentCell(self: *Self, value: CellType) void {
+            self.cells[self.coordinates.x][self.coordinates.y] = value;
         }
     };
 }
@@ -126,10 +171,7 @@ const TerrainCoordinate = u16;
 
 const Terrain = GenericTerrain(TerrainCoordinate, 1024, 1024, CellStatus);
 
-const FloodTask = struct {
+const TerrainCoordinates = Coordinates(TerrainCoordinate);
-    x: TerrainCoordinate,
-    y: TerrainCoordinate,
-};
 
 const Direction = enum(u8) {
     Right = 0,
@@ -140,24 +182,26 @@ const Direction = enum(u8) {
 
 const Command = packed struct(u32) {
     direction: Direction,
-    length: u24,
+    _: u8 = 0,
+    length: u16,
 };
 
 fn floodTerrain(terrain: *Terrain) void {
-    var queue_mem: [65_536]FloodTask = undefined;
+    var queue_mem: [65_536]TerrainCoordinates = undefined;
-    var tasks = RingQueueWrapper(FloodTask, queue_mem.len).init(&queue_mem);
+    var tasks = RingQueueWrapper(TerrainCoordinates, queue_mem.len).init(&queue_mem);
 
     tasks.add(.{ .x = 0, .y = 0 });
 
     while (!tasks.isEmpty()) {
         const task = tasks.take();
-        const x = task.x;
+        terrain.coordinates = task;
-        const y = task.y;
         //std.debug.print("Processing task for {d},{d} (current status: {any})\n", .{ x, y, terrain.*.cells[x][y] });
-        if (terrain.*.cells[x][y] == .Default) {
+        if (terrain.getCurrentCell() == .Default) {
-            terrain.*.cells[x][y] = .NotDug;
+            terrain.setCurrentCell(.NotDug);
             //std.debug.print("Marked {d},{d} as NotDug\n", .{ x, y });
 
+            const x = task.x;
+            const y = task.y;
             if (x > 0) {
                 tasks.add(.{ .x = x - 1, .y = y });
             }
@@ -194,43 +238,38 @@ fn solveForTerrain(terrain: *Terrain) usize {
     return result;
 }
 
-fn dig(terrain: *Terrain, command: Command) void {
+fn getTargetCoordinates(coordinates: TerrainCoordinates, command: Command) TerrainCoordinates {
-    const target_x = switch (command.direction) {
+    return .{
-        .Right => terrain.*.x + command.length,
+        .x = switch (command.direction) {
-        .Left => terrain.*.x - command.length,
+            .Right => coordinates.x + command.length,
-        .Up, .Down => terrain.*.x,
+            .Left => coordinates.x - command.length,
-    };
+            .Up, .Down => coordinates.x,
-
+        },
-    const target_y = switch (command.direction) {
+        .y = switch (command.direction) {
-        .Down => terrain.*.y + command.length,
+            .Down => coordinates.y + command.length,
-        .Up => terrain.*.y - command.length,
+            .Up => coordinates.y - command.length,
-        .Left, .Right => terrain.*.y,
+            .Left, .Right => coordinates.y,
+        },
     };
+}
 
-    while (terrain.*.x != target_x) {
+fn dig(terrain: *Terrain, command: Command) void {
-        if (terrain.*.x < target_x) {
+    const target = getTargetCoordinates(terrain.*.coordinates, command);
-            terrain.*.x += 1;
-        } else {
-            terrain.*.x -= 1;
-        }
 
-        terrain.*.cells[terrain.*.x][terrain.*.y] = .Dug;
+    while (!terrain.*.coordinates.isSameX(target)) {
+        terrain.*.coordinates.approachX(target);
+        terrain.*.setCurrentCell(.Dug);
     }
 
-    while (terrain.*.y != target_y) {
+    while (!terrain.*.coordinates.isSameY(target)) {
-        if (terrain.*.y < target_y) {
+        terrain.*.coordinates.approachY(target);
-            terrain.*.y += 1;
+        terrain.*.setCurrentCell(.Dug);
-        } else {
-            terrain.*.y -= 1;
-        }
-
-        terrain.*.cells[terrain.*.x][terrain.*.y] = .Dug;
     }
 }
 
 fn parseCommand(command: []const u8) Command {
     var index: usize = 2;
-    const length = readNumber(u24, command, &index);
+    const length = readNumber(u16, command, &index);
     const direction: Direction = switch (command[0]) {
         'R' => .Right,
         'L' => .Left,