82 lines
1.9 KiB
C++
82 lines
1.9 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 <tuple>
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#include <utility>
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#include <variant>
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#include <vector>
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#include <fstream>
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#include <intcode/intcode.hpp>
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using namespace intcode;
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namespace {
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using Packet = std::pair<ValueType, ValueType>;
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using Ethernet = std::deque<std::pair<std::size_t, Packet>>;
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auto BuildNetwork(Machine m) -> std::vector<Machine> {
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auto& i = std::get<Input>(Step(m)).pos;
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std::vector<Machine> machines;
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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<Packet> p) -> void {
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std::visit(overloaded{
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[&](Input i) {
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if (p) {
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i.pos = p->first;
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StepInput(m, p->second);
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Interact(ethernet, m, {});
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}
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i.pos = -1; // no packet
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},
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[&](Output d) {
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auto x = StepOutput(m);
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auto y = StepOutput(m);
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ethernet.push_back({d.val, {x,y}});
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Interact(ethernet, m, p);
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},
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[](Halt) -> void { throw std::runtime_error{"unexpected halt"}; },
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}, Step(m));
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}
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} // namespace
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auto main() -> int {
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auto machines = BuildNetwork(Machine{ParseStream(std::cin)});
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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<Packet> nat;
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for(;;) {
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if (!ethernet.empty()) {
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auto [dest, p] = ethernet.front();
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ethernet.pop_front();
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if (dest == 255) {
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nat = p;
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if (!part1) { part1 = p.second; }
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} else {
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Interact(ethernet, machines.at(dest), p);
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}
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} else if (nat) {
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if (nat->second == part2) { break; }
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part2 = nat->second;
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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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