2022-10 in zig

2022/10-cathode-ray-tube/second.zig

@@ -0,0 +1,38 @@
+const std = @import("std");
+
+const input = @embedFile("input");
+
+var result: [6 * 40]u8 = undefined;
+
+pub fn main() anyerror!void {
+    solve(input);
+    var y: usize = 0;
+    while (y < 6) : (y += 1) {
+        std.debug.print("{s}\n", .{result[y * 40 .. (y + 1) * 40]});
+    }
+}
+
+fn solve(puzzle: []const u8) void {
+    var it = std.mem.tokenize(u8, puzzle, "\n");
+    var cycle: usize = 0;
+    var x: i64 = 1;
+    var line: []const u8 = undefined;
+    var prev: ?i64 = null;
+    // process input
+    while (cycle < 40 * 6) : (cycle += 1) {
+        const pos = @mod(cycle, 40);
+        const draw = pos == x - 1 or pos == x or pos == x + 1;
+        result[cycle] = if (draw) '#' else '.';
+        if (prev) |p| { // cpu is busy adding
+            x += p;
+            prev = null;
+        } else { // read another instruction
+            line = it.next() orelse break;
+            if (line[0] == 'a') {
+                var elts = std.mem.split(u8, line, " ");
+                _ = elts.next() orelse unreachable;
+                prev = std.fmt.parseInt(i64, elts.next() orelse unreachable, 10) catch unreachable;
+            }
+        }
+    }
+}