+125
2025/1/zig/build.zig
+125
2025/1/zig/build.zig
···
1
+
const std = @import("std");
2
+
3
+
// Although this function looks imperative, it does not perform the build
4
+
// directly and instead it mutates the build graph (`b`) that will be then
5
+
// executed by an external runner. The functions in `std.Build` implement a DSL
6
+
// for defining build steps and express dependencies between them, allowing the
7
+
// build runner to parallelize the build automatically (and the cache system to
8
+
// know when a step doesn't need to be re-run).
9
+
pub fn build(b: *std.Build) void {
10
+
// Standard target options allow the person running `zig build` to choose
11
+
// what target to build for. Here we do not override the defaults, which
12
+
// means any target is allowed, and the default is native. Other options
13
+
// for restricting supported target set are available.
14
+
const target = b.standardTargetOptions(.{});
15
+
// Standard optimization options allow the person running `zig build` to select
16
+
// between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall. Here we do not
17
+
// set a preferred release mode, allowing the user to decide how to optimize.
18
+
const optimize = b.standardOptimizeOption(.{});
19
+
// It's also possible to define more custom flags to toggle optional features
20
+
// of this build script using `b.option()`. All defined flags (including
21
+
// target and optimize options) will be listed when running `zig build --help`
22
+
// in this directory.
23
+
24
+
// This creates a module, which represents a collection of source files alongside
25
+
// some compilation options, such as optimization mode and linked system libraries.
26
+
// Zig modules are the preferred way of making Zig code available to consumers.
27
+
// addModule defines a module that we intend to make available for importing
28
+
// to our consumers. We must give it a name because a Zig package can expose
29
+
// multiple modules and consumers will need to be able to specify which
30
+
// module they want to access.
31
+
32
+
// Here we define an executable. An executable needs to have a root module
33
+
// which needs to expose a `main` function. While we could add a main function
34
+
// to the module defined above, it's sometimes preferable to split business
35
+
// logic and the CLI into two separate modules.
36
+
//
37
+
// If your goal is to create a Zig library for others to use, consider if
38
+
// it might benefit from also exposing a CLI tool. A parser library for a
39
+
// data serialization format could also bundle a CLI syntax checker, for example.
40
+
//
41
+
// If instead your goal is to create an executable, consider if users might
42
+
// be interested in also being able to embed the core functionality of your
43
+
// program in their own executable in order to avoid the overhead involved in
44
+
// subprocessing your CLI tool.
45
+
//
46
+
// If neither case applies to you, feel free to delete the declaration you
47
+
// don't need and to put everything under a single module.
48
+
const exe = b.addExecutable(.{
49
+
.name = "zig",
50
+
.root_module = b.createModule(.{
51
+
// b.createModule defines a new module just like b.addModule but,
52
+
// unlike b.addModule, it does not expose the module to consumers of
53
+
// this package, which is why in this case we don't have to give it a name.
54
+
.root_source_file = b.path("src/main.zig"),
55
+
// Target and optimization levels must be explicitly wired in when
56
+
// defining an executable or library (in the root module), and you
57
+
// can also hardcode a specific target for an executable or library
58
+
// definition if desireable (e.g. firmware for embedded devices).
59
+
.target = target,
60
+
.optimize = optimize,
61
+
// List of modules available for import in source files part of the
62
+
// root module.
63
+
}),
64
+
});
65
+
66
+
// This declares intent for the executable to be installed into the
67
+
// install prefix when running `zig build` (i.e. when executing the default
68
+
// step). By default the install prefix is `zig-out/` but can be overridden
69
+
// by passing `--prefix` or `-p`.
70
+
b.installArtifact(exe);
71
+
72
+
// This creates a top level step. Top level steps have a name and can be
73
+
// invoked by name when running `zig build` (e.g. `zig build run`).
74
+
// This will evaluate the `run` step rather than the default step.
75
+
// For a top level step to actually do something, it must depend on other
76
+
// steps (e.g. a Run step, as we will see in a moment).
77
+
const run_step = b.step("run", "Run the app");
78
+
79
+
// This creates a RunArtifact step in the build graph. A RunArtifact step
80
+
// invokes an executable compiled by Zig. Steps will only be executed by the
81
+
// runner if invoked directly by the user (in the case of top level steps)
82
+
// or if another step depends on it, so it's up to you to define when and
83
+
// how this Run step will be executed. In our case we want to run it when
84
+
// the user runs `zig build run`, so we create a dependency link.
85
+
const run_cmd = b.addRunArtifact(exe);
86
+
run_step.dependOn(&run_cmd.step);
87
+
88
+
// By making the run step depend on the default step, it will be run from the
89
+
// installation directory rather than directly from within the cache directory.
90
+
run_cmd.step.dependOn(b.getInstallStep());
91
+
92
+
// This allows the user to pass arguments to the application in the build
93
+
// command itself, like this: `zig build run -- arg1 arg2 etc`
94
+
if (b.args) |args| {
95
+
run_cmd.addArgs(args);
96
+
}
97
+
98
+
// Creates an executable that will run `test` blocks from the executable's
99
+
// root module. Note that test executables only test one module at a time,
100
+
// hence why we have to create two separate ones.
101
+
const exe_tests = b.addTest(.{
102
+
.root_module = exe.root_module,
103
+
});
104
+
105
+
// A run step that will run the second test executable.
106
+
const run_exe_tests = b.addRunArtifact(exe_tests);
107
+
108
+
// A top level step for running all tests. dependOn can be called multiple
109
+
// times and since the two run steps do not depend on one another, this will
110
+
// make the two of them run in parallel.
111
+
const test_step = b.step("test", "Run tests");
112
+
test_step.dependOn(&run_exe_tests.step);
113
+
114
+
// Just like flags, top level steps are also listed in the `--help` menu.
115
+
//
116
+
// The Zig build system is entirely implemented in userland, which means
117
+
// that it cannot hook into private compiler APIs. All compilation work
118
+
// orchestrated by the build system will result in other Zig compiler
119
+
// subcommands being invoked with the right flags defined. You can observe
120
+
// these invocations when one fails (or you pass a flag to increase
121
+
// verbosity) to validate assumptions and diagnose problems.
122
+
//
123
+
// Lastly, the Zig build system is relatively simple and self-contained,
124
+
// and reading its source code will allow you to master it.
125
+
}
+44
2025/1/zig/src/main.zig
+44
2025/1/zig/src/main.zig
···
1
+
const std = @import("std");
2
+
3
+
const State = struct { turn: i32, zeroes: u32 };
4
+
5
+
pub fn main() !void {
6
+
const turns: []i32 = blk: {
7
+
const allocator = std.heap.page_allocator;
8
+
9
+
const input_raw = @embedFile("./input.txt");
10
+
const input_str = std.mem.trim(u8, input_raw, "\t\r\n");
11
+
var turns_str = std.mem.splitScalar(u8, input_str, '\n');
12
+
13
+
const turns_len =
14
+
std.mem.count(u8, input_str, "\n") + 1;
15
+
const turns = try allocator.alloc(i32, turns_len);
16
+
17
+
var i: u32 = 0;
18
+
while (turns_str.next()) |turn_str| {
19
+
const mult: i32 = if (turn_str[0] == 'L') -1 else 1;
20
+
turns[i] = try std.fmt.parseInt(i32, turn_str[1..], 10) * mult;
21
+
i += 1;
22
+
}
23
+
break :blk turns;
24
+
};
25
+
26
+
var part_1 = State{ .turn = 50, .zeroes = 0 };
27
+
for (turns) |turn| {
28
+
const iturn: i32 = @intCast(part_1.turn);
29
+
part_1.turn = @mod(iturn + turn, 100);
30
+
part_1.zeroes += @intFromBool(part_1.turn == 0);
31
+
}
32
+
std.debug.print("Part 1: {}\n", .{part_1.zeroes});
33
+
34
+
var part_2 = State{ .turn = 50, .zeroes = 0 };
35
+
for (turns) |turn| {
36
+
const iturn: i32 = @intCast(part_2.turn);
37
+
const raw_turn: i32 = iturn + turn;
38
+
// if it is below zero before being moduloed and the original number itself wasn't zero it means that it did touch zero but the division thing wouldn't count it, so we give this extra support.
39
+
// of course, there is no need to deal with a negative to positive situation because the acc.turn will never be negative!!!
40
+
part_2.zeroes += @abs(raw_turn) / 100 + @intFromBool(part_2.turn != 0 and raw_turn <= 0);
41
+
part_2.turn = @mod(raw_turn, 100);
42
+
}
43
+
std.debug.print("Part 2: {}\n", .{part_2.zeroes});
44
+
}