Advent of Code 2023

day01.zig

const std = @import("std");
const c = @cImport({
    @cInclude("raylib.h");
});

const word_numbers = [_][]const u8{
    "one",
    "two",
    "three",
    "four",
    "five",
    "six",
    "seven",
    "eight",
    "nine"
};

pub fn main() !void {
    c.InitWindow(1080, 720, "Advent of Code 2023");
    c.SetTargetFPS(60);

    const allocator = std.heap.c_allocator;
    const answer = try processPuzzleInput(allocator);
    const answer_text = try std.fmt.allocPrintZ(allocator, "The answer is: {d}", .{ answer });

    while (!c.WindowShouldClose())
    {
        c.BeginDrawing();
        defer c.EndDrawing();

        c.ClearBackground(c.RED);
        c.DrawText(answer_text, 190, 200, 20, c.GREEN);
    }

    c.CloseWindow();
}

fn processLine(line: []const u8, bReverse: bool) !i32 {
    if (line.len == 0) {
        return error.InvalidLine;
    }

    for (0..line.len) |i| {
        const char_i = if (bReverse) (line.len - i - 1) else i;
        const line_slice = line[char_i..];
        for (word_numbers, 0..) |word, word_i| {
            if (std.mem.startsWith(u8, line_slice, word)) {
                return @intCast(i32, word_i + 1);
            }
        }
        if (std.ascii.isDigit(line[char_i])) {
            return (line[char_i] - '0');
        }
    }

    return error.InvalidLine;
}

fn processPuzzleInput(allocator: std.mem.Allocator) !i32 {
    const puzzle_input = try std.fs.cwd().readFileAlloc(
        allocator, 
        "puzzle_input/day01.txt", 
        1024 * 1024
    );

    var sum: i32 = 0;
    var line_iter = std.mem.splitScalar(u8, puzzle_input, '\n');
    while (line_iter.next()) |line| {
        const first_digit: i32 = try processLine(line, false);
        const last_digit: i32 = try processLine(line, true);
        const number: i32 = (first_digit * 10) + last_digit;
        sum = sum + number;
    }

    return sum;
}