_ = @import("day25.zig");

    const day25 = @import("day25.zig");

const days = 24;

const days = 25;

15733400
6408062

const std = @import("std");
const PATH = "input/day25.txt";
const DENOMINATOR = 20201227;
pub fn first(allocator: ?std.mem.Allocator) anyerror!usize {
    _ = allocator;
    var lines = std.mem.tokenize(u8, @embedFile(PATH), "\n");
    const pub1 = try std.fmt.parseUnsigned(usize, lines.next().?, 10);
    const pub2 = try std.fmt.parseUnsigned(usize, lines.next().?, 10);
    var pkey1: usize = 1;
    var pkey2: usize = 1;
    var ekey1: usize = 1;
    var ekey2: usize = 1;
    while (true) {
        pkey1 = pkey1 * 7 % DENOMINATOR;
        pkey2 = pkey2 * 7 % DENOMINATOR;
        ekey1 = ekey1 * pub1 % DENOMINATOR;
        ekey2 = ekey2 * pub2 % DENOMINATOR;
        if (pkey1 == pub2) return ekey1;
        if (pkey2 == pub1) return ekey2;
    }
    unreachable;
}
test "day25a" {
    try std.testing.expectEqual(@as(usize, 16457981), try first(std.testing.allocator));
}
const test_input =
    \\5764801
    \\17807724
;