Refine setup

build.zig

@@ -1,35 +1,33 @@
 const std = @import("std");
 
+const nr_of_days = 12;
+
 pub fn build(b: *std.Build) void {
     const target = b.standardTargetOptions(.{});
     const optimize = b.standardOptimizeOption(.{});
 
-    // TODO: This should be a non-exhaustive enum with one option: all
-    const day = b.option(u8, "day", "Build day") orelse 1;
+    const run_all = b.step("run", "Run all days");
 
-    // TODO: Depending on the day chosen, only that day should compile, or all days
-    const exe = addDay(b, target, optimize, day);
-    b.installArtifact(exe);
+    const day_option = b.option(usize, "day", "Build day");
 
-    // run step
-    const run_exe = b.addRunArtifact(exe);
-    const run_step = b.step("run", "Run the binary");
-    run_step.dependOn(&run_exe.step);
-}
-
-fn addDay(
-    b: *std.Build,
-    target: std.Build.ResolvedTarget,
-    optimize: std.builtin.OptimizeMode,
-    day: u8,
-) *std.Build.Step.Compile {
-    return b.addExecutable(.{
-        .name = "aoc2025",
-        .root_module = b.createModule(.{
-            .root_source_file = b.path(b.fmt("src/day_{d}.zig", .{day})),
-            .target = target,
-            .optimize = optimize,
-        }),
-    });
+    for (1..nr_of_days + 1) |day| {
+        const exe = b.addExecutable(.{
+            .name = b.fmt("run-day{d:0>2}", .{day}),
+            .root_module = b.createModule(.{
+                .root_source_file = b.path("src/main.zig"),
+                .target = target,
+                .optimize = optimize,
+            }),
+        });
+        exe.root_module.addAnonymousImport("day", .{
+            .root_source_file = b.path(b.fmt("src/days/day{d:0>2}.zig", .{day})),
+        });
+        b.installArtifact(exe);
+
+        if (day_option == null or day_option == day) {
+            const run_cmd = b.addRunArtifact(exe);
+            run_all.dependOn(&run_cmd.step);
+        }
+    }
 }
 

src/day_1.zig

@@ -1,5 +0,0 @@
-const std = @import("std");
-
-pub fn main() !void {
-}
-

src/days/day01.zig

@@ -0,0 +1,8 @@
+const std = @import("std");
+
+pub const title = "Day 01: Secret Entrance";
+
+pub fn run(_: std.mem.Allocator) !void {
+    const input = @embedFile("./input/day01.txt");
+}
+

src/days/day02.zig

@@ -0,0 +1,7 @@
+const std = @import("std");
+
+pub const title = "Day 02";
+
+pub fn run(_: std.mem.Allocator) !void {
+}
+

src/days/day03.zig

@@ -0,0 +1,7 @@
+const std = @import("std");
+
+pub const title = "Day 03";
+
+pub fn run(_: std.mem.Allocator) !void {
+}
+

src/days/day04.zig

@@ -0,0 +1,7 @@
+const std = @import("std");
+
+pub const title = "Day 04";
+
+pub fn run(_: std.mem.Allocator) !void {
+}
+

src/days/day05.zig

@@ -0,0 +1,7 @@
+const std = @import("std");
+
+pub const title = "Day 05";
+
+pub fn run(_: std.mem.Allocator) !void {
+}
+

src/days/day06.zig

@@ -0,0 +1,7 @@
+const std = @import("std");
+
+pub const title = "Day 06";
+
+pub fn run(_: std.mem.Allocator) !void {
+}
+

src/days/day07.zig

@@ -0,0 +1,7 @@
+const std = @import("std");
+
+pub const title = "Day 07";
+
+pub fn run(_: std.mem.Allocator) !void {
+}
+

src/days/day08.zig

@@ -0,0 +1,7 @@
+const std = @import("std");
+
+pub const title = "Day 08";
+
+pub fn run(_: std.mem.Allocator) !void {
+}
+

src/days/day09.zig

@@ -0,0 +1,7 @@
+const std = @import("std");
+
+pub const title = "Day 09";
+
+pub fn run(_: std.mem.Allocator) !void {
+}
+

src/days/day10.zig

@@ -0,0 +1,7 @@
+const std = @import("std");
+
+pub const title = "Day 10";
+
+pub fn run(_: std.mem.Allocator) !void {
+}
+

src/days/day11.zig

@@ -0,0 +1,7 @@
+const std = @import("std");
+
+pub const title = "Day 11";
+
+pub fn run(_: std.mem.Allocator) !void {
+}
+

src/days/day12.zig

@@ -0,0 +1,7 @@
+const std = @import("std");
+
+pub const title = "Day 12";
+
+pub fn run(_: std.mem.Allocator) !void {
+}
+

src/main.zig

@@ -0,0 +1,15 @@
+const std = @import("std");
+
+const day = @import("day");
+
+pub fn main() !void {
+    var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
+    defer arena.deinit();
+
+    const allocator = arena.allocator();
+
+    std.debug.print("{s}\n", .{day.title});
+    try day.run(allocator);
+    std.debug.print("\n", .{});
+}
+