92 lines
2.1 KiB
C++
92 lines
2.1 KiB
C++
#include <cstddef>
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#include <deque>
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#include <iostream>
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#include <stdexcept>
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#include <utility>
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#include <variant>
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#include <vector>
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#include <aocpp/Startup.hpp>
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#include <intcode/intcode.hpp>
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using namespace intcode;
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namespace {
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struct Payload { ValueType x, y; };
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struct Packet { ValueType destination; Payload payload; };
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using Ethernet = std::deque<Packet>;
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auto BuildNetwork(Machine m) -> std::vector<Machine> {
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std::vector<Machine> machines;
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machines.reserve(50);
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auto& i = std::get<Input>(Step(m)).input;
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for (i = 0; i < 50; i++) {
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machines.push_back(m);
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}
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return machines;
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}
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auto Interact(Ethernet & ethernet, Machine & m, std::optional<Payload> p) -> void {
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for(;;) {
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auto e = Step(m);
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switch (e.index()) {
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default: throw std::runtime_error{"unexpected halt"};
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case 0: {
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auto& i = std::get<0>(e).input;
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if (p) {
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i = p->x;
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StepInput(m, p->y);
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p = {};
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break;
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}
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i = -1; // no packet
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return;
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}
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case 1: {
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auto d = std::get<1>(e).output;
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auto x = StepOutput(m);
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auto y = StepOutput(m);
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ethernet.push_back({d, {x,y}});
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}
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}
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}
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}
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} // namespace
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auto main(int argc, char** argv) -> int {
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auto fin = aocpp::Startup(argc, argv);
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auto machines = BuildNetwork(Machine{ParseStream(fin)});
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auto ethernet = Ethernet{};
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std::optional<ValueType> part1;
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std::optional<ValueType> part2;
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std::optional<Payload> nat;
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for(;;) {
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if (!ethernet.empty()) {
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auto packet = ethernet.front();
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ethernet.pop_front();
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if (packet.destination == 255) {
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nat = packet.payload;
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if (!part1) { part1 = packet.payload.y; }
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} else {
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Interact(ethernet, machines.at(packet.destination), packet.payload);
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}
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} else if (nat) {
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if (part2 == nat->y) { break; }
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part2 = nat->y;
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Interact(ethernet, machines[0], nat);
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} else {
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for (auto & m : machines) {
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Interact(ethernet, m, {});
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}
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}
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}
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std::cout << "Part 1: " << *part1 << std::endl;
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std::cout << "Part 2: " << *part2 << std::endl;
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}
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