day1

5 files changed, 206 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..ddd6cad
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+input.txt
+.zig-cache
+zig-out
diff --git a/day1/zig/build.zig b/day1/zig/build.zig
new file mode 100644
index 0000000..ec66699
--- /dev/null
+++ b/day1/zig/build.zig
@@ -0,0 +1,39 @@
+const std = @import("std");
+
+pub fn build(b: *std.Build) void {
+    const target = b.standardTargetOptions(.{});
+    const optimize = b.standardOptimizeOption(.{});
+
+    const exe = b.addExecutable(.{
+        .name = "zig",
+        .root_module = b.createModule(.{
+            .root_source_file = b.path("src/main.zig"),
+            .target = target,
+            .optimize = optimize,
+            .imports = &.{},
+        }),
+    });
+
+    b.installArtifact(exe);
+
+    const run_step = b.step("run", "Run the app");
+
+    const run_cmd = b.addRunArtifact(exe);
+    run_step.dependOn(&run_cmd.step);
+
+    run_cmd.step.dependOn(b.getInstallStep());
+
+    if (b.args) |args| {
+        run_cmd.addArgs(args);
+    }
+
+    const exe_tests = b.addTest(.{
+        .root_module = exe.root_module,
+    });
+
+    const run_exe_tests = b.addRunArtifact(exe_tests);
+
+    const test_step = b.step("test", "Run tests");
+    test_step.dependOn(&run_exe_tests.step);
+
+}
diff --git a/day1/zig/build.zig.zon b/day1/zig/build.zig.zon
new file mode 100644
index 0000000..aa8bb7c
--- /dev/null
+++ b/day1/zig/build.zig.zon
@@ -0,0 +1,81 @@
+.{
+    // This is the default name used by packages depending on this one. For
+    // example, when a user runs `zig fetch --save <url>`, this field is used
+    // as the key in the `dependencies` table. Although the user can choose a
+    // different name, most users will stick with this provided value.
+    //
+    // It is redundant to include "zig" in this name because it is already
+    // within the Zig package namespace.
+    .name = .zig,
+    // This is a [Semantic Version](https://semver.org/).
+    // In a future version of Zig it will be used for package deduplication.
+    .version = "0.0.0",
+    // Together with name, this represents a globally unique package
+    // identifier. This field is generated by the Zig toolchain when the
+    // package is first created, and then *never changes*. This allows
+    // unambiguous detection of one package being an updated version of
+    // another.
+    //
+    // When forking a Zig project, this id should be regenerated (delete the
+    // field and run `zig build`) if the upstream project is still maintained.
+    // Otherwise, the fork is *hostile*, attempting to take control over the
+    // original project's identity. Thus it is recommended to leave the comment
+    // on the following line intact, so that it shows up in code reviews that
+    // modify the field.
+    .fingerprint = 0xc1ce10815e998101, // Changing this has security and trust implications.
+    // Tracks the earliest Zig version that the package considers to be a
+    // supported use case.
+    .minimum_zig_version = "0.15.1",
+    // This field is optional.
+    // Each dependency must either provide a `url` and `hash`, or a `path`.
+    // `zig build --fetch` can be used to fetch all dependencies of a package, recursively.
+    // Once all dependencies are fetched, `zig build` no longer requires
+    // internet connectivity.
+    .dependencies = .{
+        // See `zig fetch --save <url>` for a command-line interface for adding dependencies.
+        //.example = .{
+        //    // When updating this field to a new URL, be sure to delete the corresponding
+        //    // `hash`, otherwise you are communicating that you expect to find the old hash at
+        //    // the new URL. If the contents of a URL change this will result in a hash mismatch
+        //    // which will prevent zig from using it.
+        //    .url = "https://example.com/foo.tar.gz",
+        //
+        //    // This is computed from the file contents of the directory of files that is
+        //    // obtained after fetching `url` and applying the inclusion rules given by
+        //    // `paths`.
+        //    //
+        //    // This field is the source of truth; packages do not come from a `url`; they
+        //    // come from a `hash`. `url` is just one of many possible mirrors for how to
+        //    // obtain a package matching this `hash`.
+        //    //
+        //    // Uses the [multihash](https://multiformats.io/multihash/) format.
+        //    .hash = "...",
+        //
+        //    // When this is provided, the package is found in a directory relative to the
+        //    // build root. In this case the package's hash is irrelevant and therefore not
+        //    // computed. This field and `url` are mutually exclusive.
+        //    .path = "foo",
+        //
+        //    // When this is set to `true`, a package is declared to be lazily
+        //    // fetched. This makes the dependency only get fetched if it is
+        //    // actually used.
+        //    .lazy = false,
+        //},
+    },
+    // Specifies the set of files and directories that are included in this package.
+    // Only files and directories listed here are included in the `hash` that
+    // is computed for this package. Only files listed here will remain on disk
+    // when using the zig package manager. As a rule of thumb, one should list
+    // files required for compilation plus any license(s).
+    // Paths are relative to the build root. Use the empty string (`""`) to refer to
+    // the build root itself.
+    // A directory listed here means that all files within, recursively, are included.
+    .paths = .{
+        "build.zig",
+        "build.zig.zon",
+        "src",
+        // For example...
+        //"LICENSE",
+        //"README.md",
+    },
+}
diff --git a/day1/zig/src/input_sample.txt b/day1/zig/src/input_sample.txt
new file mode 100644
index 0000000..53287c7
--- /dev/null
+++ b/day1/zig/src/input_sample.txt
@@ -0,0 +1,10 @@
+L68
+L30
+R48
+L5
+R60
+L55
+L1
+L99
+R14
+L82
diff --git a/day1/zig/src/main.zig b/day1/zig/src/main.zig
new file mode 100644
index 0000000..6520d5f
--- /dev/null
+++ b/day1/zig/src/main.zig
@@ -0,0 +1,73 @@
+const std = @import("std");
+const mem = std.mem;
+const math = std.math;
+
+pub fn main() !void {
+    const input: []const u8 = @embedFile("input.txt");
+    const part1, const part2 = try problem(input);
+    std.debug.print("Part 1: {}\n", .{part1});
+    std.debug.print("Part 2: {}\n", .{part2});
+}
+
+fn problem(input: []const u8) !struct { u64, u64 } {
+    const lines: mem.TokenIterator(u8, .scalar) = mem.tokenizeScalar(u8, input, '\n');
+    const part1: u64 = try p1(lines);
+    const part2: u64 = try p2(lines);
+    return .{ part1, part2 };
+}
+
+fn parseline(l: []const u8) !i64 {
+    return switch (l[0]) {
+        'L' => try std.fmt.parseInt(i64, l[1..], 10),
+        'R' => - try std.fmt.parseInt(i64, l[1..], 10),
+        else => error{InvalidLine}.InvalidLine,
+    };
+}
+
+inline fn rotatepos(pos: u32, n: i64) u32 {
+    return @truncate(@abs(@mod(pos + n, 100)));
+}
+
+fn countzeros(pos: u64, n: i64) u64 {
+    var zeros: u64 = 0;
+    var x: u32 = @intCast(pos);
+    var clicks: u64 = @abs(n);
+    const y: i64 = if (n < 0) -1 else 1;
+    while (clicks > 0) : (clicks -= 1){
+        x = rotatepos(x, y);
+        if (x == 0) zeros += 1;
+    }
+    return zeros;
+}
+
+fn p1(constLines: mem.TokenIterator(u8, .scalar)) !u64 {
+    var pos: u32 = 50;
+    var zeros: u64 = 0;
+    var lines = constLines;
+    while (lines.next()) |line| {
+        pos = rotatepos(pos, try parseline(line));
+        if (pos == 0) zeros += 1;
+    }
+    return zeros;
+}
+
+fn p2(constLines: mem.TokenIterator(u8, .scalar)) !u64 {
+    var pos: u32 = 50;
+    var zeros: u64 = 0;
+    var lines = constLines;
+    while (lines.next()) |line| {
+        const n = try parseline(line);
+        zeros += countzeros(pos, n);
+        pos = rotatepos(pos, n);
+    }
+    return zeros;
+}
+
+test "Sample Input" {
+    const input: []const u8 = @embedFile("input_sample.txt");
+    const part1, const part2 = try problem(input);
+    std.debug.print("Part 1: {}\n", .{part1});
+    std.debug.print("Part 2: {}\n", .{part2});
+    try std.testing.expectEqual(3, part1);
+    try std.testing.expectEqual(6, part2);
+}