Day 11, part 2

11/src/main.zig

@@ -1,8 +1,8 @@
 const std = @import("std");
 const intcode = @import("intcode");
 
-const boardX = 1024;
+const boardX = 155;
-const boardY = 1024;
+const boardY = 100;
 
 const Point = struct {
     x: usize,
@@ -67,11 +67,8 @@ fn runMachine(m: *intcode.Machine) void {
     }
 }
 
-pub fn main() anyerror!void {
+fn run(alloc: *std.mem.Allocator, program: []intcode.Word, part1: bool) !void {
-    var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
+    const part2 = !part1;
-    defer arena.deinit();
-
-    const alloc = &arena.allocator;
 
     var board: Board = undefined;
     for (board) |*row| {
@@ -84,8 +81,11 @@ pub fn main() anyerror!void {
     var pos = Point{.x = boardX / 2, .y = boardY / 2};
     var direction = Compass.North;
 
-    var program = try intcode.loadFromStdIn(alloc);
+    // Start on a white panel in part 2
+    if (part2) board[pos.y][pos.x].colour = .White;
+
     var machine = try intcode.Machine.init(alloc, program);
+    defer machine.deinit();
     var robot = try std.Thread.spawn(&machine, runMachine);
 
     // Robot event loop
@@ -111,12 +111,36 @@ pub fn main() anyerror!void {
 
     robot.wait();
 
-    var touched: usize = 0;
+    if (part1) {
-    for (board) |row| {
+        var touched: usize = 0;
-        for (row) |cell| {
+        for (board) |row| {
-            if (cell.touched) touched += 1;
+            for (row) |cell| {
+                if (cell.touched) touched += 1;
+            }
+        }
+
+        std.debug.warn("Day 11, Part 1: {}\n", touched);
+    } else {
+        for (board) |row| {
+            for (row) |cell| {
+                switch (cell.colour) {
+                    .Black => std.debug.warn(" "),
+                    .White => std.debug.warn("#"),
+                }
+            }
+            std.debug.warn("\n");
         }
     }
-
+}
-    std.debug.warn("Day 11, Part 1: {}\n", touched);
+
+pub fn main() anyerror!void {
+    var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
+    defer arena.deinit();
+
+    const alloc = &arena.allocator;
+
+    var program = try intcode.loadFromStdIn(alloc);
+
+    try run(alloc, program, true);
+    try run(alloc, program, false);
 }