const DAYS = 5;

const DAYS = 6;

    const day06 = @import("day06.zig");

    _ = @import("day06.zig");

Time:        40     92     97     90
Distance:   215   1064   1505   1100

const std = @import("std");
const PATH = "input/day06.txt";
pub fn first(allocator: std.mem.Allocator) !usize {
    const races = try parseInput(allocator, @embedFile(PATH));
    defer allocator.free(races);
    var ret: usize = 1;
    for (races) |race| {
        var beaten: usize = 0;
        for (0..race.time) |speed| {
            const d = speed * (race.time - speed);
            if (d > race.distance) beaten += 1;
        }
        ret *= beaten;
    }
    return ret;
}
pub fn second(allocator: std.mem.Allocator) !usize {
    var race: struct { time: u32, distance: usize } = undefined;
    var buf = std.ArrayList(u8).init(allocator);
    defer buf.deinit();
    var lines = std.mem.splitScalar(u8, @embedFile(PATH), '\n');
    {
        const line = lines.next().?;
        for (line) |ch| {
            switch (ch) {
                '0'...'9' => {
                    try buf.append(ch);
                },
                else => {},
            }
        }
        race.time = try std.fmt.parseUnsigned(u32, buf.items, 10);
    }
    {
        try buf.resize(0);
        for (lines.next().?) |ch| {
            switch (ch) {
                '0'...'9' => {
                    try buf.append(ch);
                },
                else => {},
            }
        }
        race.distance = try std.fmt.parseUnsigned(usize, buf.items, 10);
    }
    var beaten: usize = 0;
    for (0..race.time) |speed| {
        const d = speed * (race.time - speed);
        if (d > race.distance) beaten += 1;
    }
    return beaten;
}
const Race = struct {
    time: u8,
    distance: u16,
};
fn parseInput(allocator: std.mem.Allocator, input: []const u8) ![]Race {
    var races = std.ArrayList(Race).init(allocator);
    var lines = std.mem.splitScalar(u8, input, '\n');
    var line = lines.next().?;
    var times = std.mem.tokenizeScalar(u8, line, ' ');
    _ = times.next(); // drop "Time:"
    while (times.next()) |time| {
        var r: Race = undefined;
        const t = try std.fmt.parseUnsigned(u8, time, 10);
        r.time = t;
        try races.append(r);
    }
    line = lines.next().?;
    var distances = std.mem.tokenizeScalar(u8, line, ' ');
    _ = distances.next(); // drop "Distance:"
    var i: usize = 0;
    while (distances.next()) |distance| {
        const d = try std.fmt.parseUnsigned(u16, distance, 10);
        races.items[i].distance = d;
        i += 1;
    }
    return races.toOwnedSlice();
}
test "day06a" {
    try std.testing.expectEqual(@as(usize, 6209190), try first(std.testing.allocator));
}
test "day06b" {
    try std.testing.expectEqual(@as(usize, 28545089), try second(std.testing.allocator));
}
const test_input =
    \\Time:      7  15   30
    \\Distance:  9  40  200
;