day 20!
That took a while
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299
AdventOfCode2023/src/day20/day20.zig
Normal file
299
AdventOfCode2023/src/day20/day20.zig
Normal file
@ -0,0 +1,299 @@
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const std = @import("std");
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const print = std.debug.print;
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fn gcd(a: usize, b: usize) usize {
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if (b == 0) {
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return a;
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}
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return gcd(b, a % b);
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}
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fn lcm(a: usize, b: usize) usize {
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return (a / gcd(a, b)) * b;
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}
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const Node = std.DoublyLinkedList(SendingPulse).Node;
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const ModuleType = enum { flipflop, conjunction, broadcaster };
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const FlipFlop = struct {
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is_on: bool,
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name: []const u8, // string
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outputs: []const u8,
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};
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const Conjunction = struct {
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memory: []SendingPulse,
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name: []const u8, // string
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outputs: []const u8,
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};
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const Broadcaster = struct {
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name: []const u8, // string
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outputs: []u8,
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};
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const Module = union(ModuleType) {
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flipflop: FlipFlop,
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conjunction: Conjunction,
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broadcaster: Broadcaster,
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};
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const SendingPulse = struct {
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from: u8,
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to: u8,
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pulse: bool,
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};
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const UNNAMED: u8 = 255;
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// pulse = true = high
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fn send_pulse(allocator: std.mem.Allocator, module_map: *std.AutoHashMap(u8, Module), queue: *std.DoublyLinkedList(SendingPulse), module_index: u8, pulse: SendingPulse) !void {
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var module = module_map.get(module_index).?;
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switch (module) {
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ModuleType.broadcaster => {
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for (module.broadcaster.outputs) |output| {
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const n = try allocator.create(Node);
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n.*.data = SendingPulse{ .pulse = pulse.pulse, .from = module_index, .to = output };
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queue.*.append(n);
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}
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},
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ModuleType.flipflop => {
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if (pulse.pulse) {
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// FlipFlip doesnt to anything on a high pulse
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return;
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}
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module.flipflop.is_on = !module.flipflop.is_on;
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for (module.flipflop.outputs) |output| {
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const n = try allocator.create(Node);
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n.*.data = SendingPulse{ .pulse = module.flipflop.is_on, .from = module_index, .to = output };
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queue.append(n);
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}
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try module_map.put(module_index, module);
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},
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ModuleType.conjunction => {
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const memory_index = for (module.conjunction.memory, 0..) |memory, i| {
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if (memory.from == pulse.from) {
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break i;
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}
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} else unreachable;
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module.conjunction.memory[memory_index] = pulse;
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const all_memory_high = for (module.conjunction.memory) |memory| {
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if (!memory.pulse) {
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break false;
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}
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} else true;
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for (module.conjunction.outputs) |output| {
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const n = try allocator.create(Node);
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n.*.data = SendingPulse{ .pulse = !all_memory_high, .from = module_index, .to = output };
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queue.append(n);
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}
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try module_map.put(module_index, module);
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},
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}
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}
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pub fn solve(input: [][]const u8) !void {
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const allocator = std.heap.page_allocator;
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var name_to_number = std.StringHashMap(u8).init(allocator);
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defer name_to_number.deinit();
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var module_map = std.AutoHashMap(u8, Module).init(allocator);
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defer module_map.deinit();
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var broadcaster_index: u8 = 0;
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for (input, 0..) |line, index| {
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var arrow_tokenizer = std.mem.tokenizeSequence(u8, line, " -> ");
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var module = arrow_tokenizer.next().?;
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const module_type = module[0];
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module = module[1..];
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const built_module = switch (module_type) {
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'%' => Module{ .flipflop = FlipFlop{ .is_on = false, .name = module, .outputs = undefined } },
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'&' => Module{ .conjunction = Conjunction{ .memory = &[_]SendingPulse{}, .name = module, .outputs = undefined } },
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'b' => Module{ .broadcaster = Broadcaster{ .name = module, .outputs = undefined } },
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else => unreachable,
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};
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switch (built_module) {
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ModuleType.broadcaster => {
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broadcaster_index = @truncate(index);
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},
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else => {},
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}
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try name_to_number.put(module, @truncate(index));
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try module_map.put(@truncate(index), built_module);
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}
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for (input, 0..) |line, index| {
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var arrow_tokenizer = std.mem.tokenizeSequence(u8, line, " -> ");
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_ = arrow_tokenizer.next().?;
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const output_names = arrow_tokenizer.next().?;
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var outputs: [10]u8 = undefined;
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var output_index: usize = 0;
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var output_tokenizer = std.mem.tokenizeSequence(u8, output_names, ", ");
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while (output_tokenizer.next()) |output| {
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const output_module_number = name_to_number.get(output) orelse UNNAMED;
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outputs[output_index] = output_module_number;
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output_index += 1;
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var output_module = module_map.get(output_module_number) orelse continue;
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switch (output_module) {
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ModuleType.conjunction => {
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var new_memory = try allocator.alloc(SendingPulse, output_module.conjunction.memory.len + 1);
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std.mem.copyForwards(SendingPulse, new_memory, output_module.conjunction.memory);
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new_memory[new_memory.len - 1] = SendingPulse{ .to = 0, .from = @truncate(index), .pulse = false };
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output_module.conjunction.memory = new_memory;
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try module_map.put(output_module_number, output_module);
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},
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else => {},
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}
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}
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var copied_outputs = try allocator.alloc(u8, output_index);
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for (0..output_index) |i| {
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copied_outputs[i] = outputs[i];
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}
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var module = module_map.get(@truncate(index)).?;
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switch (module) {
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ModuleType.broadcaster => module.broadcaster.outputs = copied_outputs,
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ModuleType.flipflop => module.flipflop.outputs = copied_outputs,
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ModuleType.conjunction => module.conjunction.outputs = copied_outputs,
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}
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try module_map.put(@truncate(index), module);
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}
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var work_queue = std.DoublyLinkedList(SendingPulse){};
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var low: usize = 0;
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var high: usize = 0;
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const PART_1 = 1000;
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for (0..PART_1) |_| {
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var n = try allocator.create(Node);
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n.data = SendingPulse{ .from = 0, .to = broadcaster_index, .pulse = false };
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work_queue.append(n);
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while (work_queue.len > 0) {
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const pulse = work_queue.popFirst().?;
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if (pulse.data.pulse) {
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high += 1;
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} else {
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low += 1;
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}
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if (pulse.data.to == UNNAMED) {
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allocator.destroy(pulse);
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continue;
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}
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try send_pulse(allocator, &module_map, &work_queue, pulse.data.to, pulse.data);
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allocator.destroy(pulse);
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}
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}
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const part1 = low * high;
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var part2: usize = 0;
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var module_iter = module_map.iterator();
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while (module_iter.next()) |entry| {
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var module = entry.value_ptr.*;
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switch (module) {
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ModuleType.flipflop => {
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module.flipflop.is_on = false;
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try module_map.put(entry.key_ptr.*, module);
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},
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ModuleType.conjunction => {
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for (0..module.conjunction.memory.len) |memory_index| {
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module.conjunction.memory[memory_index].pulse = false;
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}
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try module_map.put(entry.key_ptr.*, module);
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},
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else => {},
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}
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}
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const MR = name_to_number.get("mr").?;
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const KK = name_to_number.get("kk").?;
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const GL = name_to_number.get("gl").?;
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const BB = name_to_number.get("bb").?;
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var mr_loop: usize = 0;
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var kk_loop: usize = 0;
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var gl_loop: usize = 0;
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var bb_loop: usize = 0;
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var loop_counter: usize = 0;
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topLoop: while (true) {
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loop_counter += 1;
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var n = try allocator.create(Node);
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n.data = SendingPulse{ .from = 0, .to = broadcaster_index, .pulse = false };
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work_queue.append(n);
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while (work_queue.len > 0) {
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const pulse = work_queue.popFirst().?;
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if (mr_loop == 0 and pulse.data.from == MR and pulse.data.pulse) {
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print("Setting mr_loop: {}\n", .{loop_counter});
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mr_loop = loop_counter;
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}
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if (kk_loop == 0 and pulse.data.from == KK and pulse.data.pulse) {
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print("Setting kk_loop: {}\n", .{loop_counter});
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kk_loop = loop_counter;
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}
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if (gl_loop == 0 and pulse.data.from == GL and pulse.data.pulse) {
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print("Setting gl_loop: {}\n", .{loop_counter});
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gl_loop = loop_counter;
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}
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if (bb_loop == 0 and pulse.data.from == BB and pulse.data.pulse) {
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print("Setting bb_loop: {}\n", .{loop_counter});
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bb_loop = loop_counter;
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}
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if (mr_loop != 0 and kk_loop != 0 and gl_loop != 0 and bb_loop != 0) {
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part2 = lcm(mr_loop, lcm(kk_loop, lcm(gl_loop, bb_loop)));
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break :topLoop;
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}
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if (pulse.data.to == UNNAMED) {
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allocator.destroy(pulse);
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continue;
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}
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try send_pulse(allocator, &module_map, &work_queue, pulse.data.to, pulse.data);
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allocator.destroy(pulse);
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}
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}
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print("Part 1: {}\n", .{part1});
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print("Part 2: {}\n", .{part2});
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}
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@ -16,7 +16,8 @@ const std = @import("std");
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// const day16 = @import("./day16/day16.zig");
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// const day17 = @import("./day17/day17.zig");
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// const day18 = @import("./day18/day18.zig");
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const day19 = @import("./day19/day19.zig");
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// const day19 = @import("./day19/day19.zig");
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const day20 = @import("./day20/day20.zig");
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// const day21 = @import("./day21/day21.zig");
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// const day23 = @import("./day23/day23.zig");
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// const day24 = @import("./day24/day24.zig");
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@ -24,8 +25,8 @@ const utils = @import("utils.zig");
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pub fn main() !void {
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const allocator = std.heap.page_allocator;
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const input = try utils.getInput("./src/day19/input.txt", allocator);
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const input = try utils.getInput("./src/day20/input.txt", allocator);
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defer allocator.free(input);
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try day19.solve(input);
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try day20.solve(input);
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}
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