advent-of-code/2015/day1.zig

const std = @import("std");

fn part1(directions: std.ArrayList(u8), floor: *i16) void {
    for (directions.items) |direction| {
        if (direction == '(') {
            floor.* += 1;
        } else if (direction == ')') {
            floor.* -= 1;
        }
    }
}

fn part2(directions: std.ArrayList(u8), pos: *i16) void {
    var floor: i16 = 0;
    for (directions.items) |direction| {
        if (direction == '(') {
            floor += 1;
        } else if (direction == ')') {
            floor -= 1;
        }
        pos.* += 1;

        if (floor == -1) break;
    }
}

pub fn main() !void {
    const file = try std.fs.cwd().openFile("day1.txt", .{});
    defer file.close();

    var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
    defer arena.deinit();
    const alloc = arena.allocator();

    var buf = std.io.bufferedReader(file.reader());

    var directions = std.ArrayList(u8).init(alloc);
    defer directions.deinit();

    while (true) {
        buf.reader().streamUntilDelimiter(directions.writer(), '\n', null) catch |err| switch (err) {
            error.EndOfStream => break,
            else => return err,
        };
    }

    var floor: i16 = 0;
    var position: i16 = 0;

    part1(directions, &floor);
    part2(directions, &position);

    std.debug.print("Ending floor: {d}\n", .{floor});
    std.debug.print("Position when first entering basement: {d}\n", .{position});
}