src/day08.zig

@@ -1,104 +0,0 @@
-const std = @import("std");
-const util = @import("util.zig");
-const mem = std.mem;
-
-pub fn main() !void {
-    const input = @embedFile("data/day08.txt");
-    const sln = try solve(util.gpa, input);
-    std.debug.print("{d}\n", .{sln.a});
-    std.debug.print("{d}\n", .{sln.b});
-}
-
-const Solution = struct {
-    a: usize,
-    b: usize,
-};
-
-const Step = struct {
-    left: [3]u8,
-    right: [3]u8,
-};
-
-fn gcd(a: usize, b: usize) usize {
-    return if (b == 0) a else gcd(b, a % b);
-}
-
-fn lcm(ns: []u32) usize {
-    var acc: usize = ns[0];
-    for (ns[1..]) |n| {
-        const nsize = @as(usize, n);
-        acc = acc / gcd(acc, nsize) * nsize;
-    }
-    return acc;
-}
-
-fn solve(alloc: mem.Allocator, input: []const u8) !Solution {
-    var states = std.AutoHashMap([3]u8, Step).init(alloc);
-    defer states.deinit();
-
-    var it = util.splitLines(input);
-    const steps = it.next().?;
-    while (it.next()) |line| {
-        if (line.len == 0) continue;
-        try states.put(line[0..3].*, .{ .left = line[7..10].*, .right = line[12..15].* });
-    }
-
-    var a_nodes = std.AutoHashMap([3]u8, Step).init(alloc);
-    defer a_nodes.deinit();
-    var state_it = states.iterator();
-    while (state_it.next()) |entry| {
-        if (entry.key_ptr[2] == 'A') {
-            try a_nodes.put(entry.key_ptr.*, entry.value_ptr.*);
-        }
-    }
-
-    var all_steps = std.ArrayList(u32).init(alloc);
-    defer all_steps.deinit();
-    var a_it = a_nodes.iterator();
-    while (a_it.next()) |start| {
-        std.debug.print("{s}\n", .{start.key_ptr});
-        var position: [3]u8 = start.key_ptr.*;
-        var count: u32 = 0;
-        find: while (position[2] != 'Z') : (count += 1) {
-            const curr_state = states.get(position) orelse break :find; // ???????
-            position = if (steps[count % steps.len] == 'L') curr_state.left else curr_state.right;
-        }
-        try all_steps.append(count);
-    }
-
-    return .{ .a = 2, .b = lcm(all_steps.items) };
-}
-
-test "silver" {
-    const input =
-        \\RL
-        \\
-        \\AAA = (BBB, CCC)
-        \\BBB = (DDD, EEE)
-        \\CCC = (ZZZ, GGG)
-        \\DDD = (DDD, DDD)
-        \\EEE = (EEE, EEE)
-        \\GGG = (GGG, GGG)
-        \\ZZZ = (ZZZ, ZZZ)
-    ;
-    _ = input;
-    // const sln = try solve(std.testing.allocator, input);
-    // try std.testing.expectEqual(@as(usize, 2), sln.a);
-}
-
-test "gold" {
-    const input =
-        \\LR
-        \\
-        \\11A = (11B, XXX)
-        \\11B = (XXX, 11Z)
-        \\11Z = (11B, XXX)
-        \\22A = (22B, XXX)
-        \\22B = (22C, 22C)
-        \\22C = (22Z, 22Z)
-        \\22Z = (22B, 22B)
-        \\XXX = (XXX, XXX)
-    ;
-    const sln = try solve(std.testing.allocator, input);
-    try std.testing.expectEqual(@as(usize, 6), sln.b);
-}