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day 2

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Lucia Ceionia
2024-12-02 00:21:59 -06:00
parent 551311fca6
commit 398a587d95
3 changed files with 301 additions and 0 deletions
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66
02/build.zig Normal file
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const std = @import("std");
// Although this function looks imperative, note that its job is to
// declaratively construct a build graph that will be executed by an external
// runner.
pub fn build(b: *std.Build) void {
// Standard target options allows the person running `zig build` to choose
// what target to build for. Here we do not override the defaults, which
// means any target is allowed, and the default is native. Other options
// for restricting supported target set are available.
const target = b.standardTargetOptions(.{});
// Standard optimization options allow the person running `zig build` to select
// between Debug, ReleaseSafe, ReleaseFast, and ReleaseSmall. Here we do not
// set a preferred release mode, allowing the user to decide how to optimize.
const optimize = b.standardOptimizeOption(.{});
const exe = b.addExecutable(.{
.name = "02",
.root_source_file = b.path("src/main.zig"),
.target = target,
.optimize = optimize,
});
// This declares intent for the executable to be installed into the
// standard location when the user invokes the "install" step (the default
// step when running `zig build`).
b.installArtifact(exe);
// This *creates* a Run step in the build graph, to be executed when another
// step is evaluated that depends on it. The next line below will establish
// such a dependency.
const run_cmd = b.addRunArtifact(exe);
// By making the run step depend on the install step, it will be run from the
// installation directory rather than directly from within the cache directory.
// This is not necessary, however, if the application depends on other installed
// files, this ensures they will be present and in the expected location.
run_cmd.step.dependOn(b.getInstallStep());
// This allows the user to pass arguments to the application in the build
// command itself, like this: `zig build run -- arg1 arg2 etc`
if (b.args) |args| {
run_cmd.addArgs(args);
}
// This creates a build step. It will be visible in the `zig build --help` menu,
// and can be selected like this: `zig build run`
// This will evaluate the `run` step rather than the default, which is "install".
const run_step = b.step("run", "Run the app");
run_step.dependOn(&run_cmd.step);
const exe_unit_tests = b.addTest(.{
.root_source_file = b.path("src/main.zig"),
.target = target,
.optimize = optimize,
});
const run_exe_unit_tests = b.addRunArtifact(exe_unit_tests);
// Similar to creating the run step earlier, this exposes a `test` step to
// the `zig build --help` menu, providing a way for the user to request
// running the unit tests.
const test_step = b.step("test", "Run unit tests");
test_step.dependOn(&run_exe_unit_tests.step);
}

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.{
// 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 = "02",
// 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",
// This field is optional.
// This is currently advisory only; Zig does not yet do anything
// with this value.
//.minimum_zig_version = "0.11.0",
// 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.
// .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",
},
}

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02/src/main.zig Normal file
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// Day 2! Yea. Still not idiomatic.
// Implementation of both sucks bad.
// Whatever
const std = @import("std");
var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
const alloc = arena.allocator();
const test_data = @embedFile("test");
const input_data = @embedFile("input");
pub fn main() !void {
const stdout = std.io.getStdOut().writer();
const value1 = try run1(input_data);
try stdout.print("{d}\n", .{value1});
const value2 = try run2(input_data);
try stdout.print("{d}\n", .{value2});
}
test "test input part 1" {
const value = try run1(test_data);
std.debug.print("{d}\n", .{value});
try std.testing.expectEqual(value, 2);
}
test "test input part 2" {
const value = try run2(test_data);
std.debug.print("{d}\n", .{value});
try std.testing.expectEqual(value, 4);
}
// this sucks and i don't know if i actually
// need to check all these cases
// ...but it's fast still
fn check_good(a: []i64) u64 {
if (a.len < 2) {
return 0;
}
var skip_i: i64 = -1;
attempt: while (true) {
var last: i64 = 0;
var good: u64 = 1;
var c: usize = 0;
var desc: bool = false;
var i: usize = 0;
line: while (i < a.len) {
if (i == skip_i) {
i += 1;
continue;
}
const dif = last - a[i];
const abs = @abs(dif);
switch (c) {
0 => {},
1 => {
desc = dif < 0;
if (abs < 1 or abs > 3) {
good = 0;
break :line;
}
},
else => {
if ((dif < 0) != desc or abs < 1 or abs > 3) {
good = 0;
break :line;
}
},
}
last = a[i];
c += 1;
i += 1;
}
if (good == 0) {
skip_i += 1;
if (skip_i == a.len) {
return 0;
}
continue :attempt;
} else {
return 1;
}
}
}
fn run2(s: []const u8) !u64 {
var lines = std.mem.splitScalar(u8, s, '\n');
var total: u64 = 0;
var arr = std.ArrayList(i64).init(alloc);
while (lines.next()) |line| {
arr.clearRetainingCapacity();
var split = std.mem.splitScalar(u8, line, ' ');
while (split.next()) |i| {
if (std.mem.eql(u8, i, "")) continue;
const num = try std.fmt.parseInt(i64, i, 10);
try arr.append(num);
}
if (arr.items.len == 0) continue;
const good = check_good(arr.items);
std.debug.print("{s} safe: {d}\n", .{ line, good });
total += good;
}
return total;
}
fn run1(s: []const u8) !u64 {
var lines = std.mem.splitScalar(u8, s, '\n');
var total: u64 = 0;
while (lines.next()) |line| {
var split = std.mem.splitScalar(u8, line, ' ');
var last: i64 = 0;
var good: u64 = 1;
var desc: bool = true;
var c: usize = 0;
line: while (split.next()) |i| {
if (std.mem.eql(u8, i, "")) continue;
const num = try std.fmt.parseInt(i64, i, 10);
const dif = last - num;
const abs = @abs(dif);
switch (c) {
0 => {},
1 => {
desc = dif < 0;
if (abs < 1 or abs > 3) {
good = 0;
break :line;
}
},
else => {
if ((dif < 0) != desc or abs < 1 or abs > 3) {
good = 0;
break :line;
}
},
}
last = num;
c += 1;
}
if (c < 2) continue;
std.debug.print("{s} safe: {d}\n", .{ line, good });
total += good;
}
return total;
}