Initial commit

build.zig

@@ -0,0 +1,35 @@
+const std = @import("std");
+
+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;
+
+    // TODO: Depending on the day chosen, only that day should compile, or all days
+    const exe = addDay(b, target, optimize, day);
+    b.installArtifact(exe);
+
+    // 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,
+        }),
+    });
+}
+