66 lines
1.4 KiB
C++
66 lines
1.4 KiB
C++
#include <deque>
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#include <iostream>
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#include <set>
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#include <tuple>
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#include <utility>
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#include <intcode/intcode.hpp>
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#include <intcode/Coord.hpp>
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using namespace intcode;
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namespace {
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std::pair<ValueType, Coord(*)(Coord)> const moves[4]
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{{1, Up}, {2, Down}, {3, Left}, {4, Right}};
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auto Fork(Machine m, ValueType cmd) {
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std::get<Input>(Step(m)).pos = cmd;
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auto o = std::get<Output>(Step(m)).val;
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return std::make_pair(o, std::move(m));
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}
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auto Compute(Machine machine) {
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Coord const origin {0,0};
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std::set<Coord> world {origin};
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std::deque<std::tuple<int, Coord, Machine>> todo
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{{0, origin, std::move(machine)}};
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long part1 = -1;
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long part2 = -1;
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top:
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while (!todo.empty()) {
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auto & [steps, loc, m] = todo.front();
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part2 = steps;
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steps++;
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for (auto&& [cmd, fun] : moves) {
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auto loc_ = fun(loc);
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if (world.insert(loc_).second) {
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auto [o,m_] = Fork(m, cmd);
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switch (o) {
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case 2:
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part1 = steps;
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world = {origin};
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todo = {{0, origin, std::move(m_)}};
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goto top;
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case 1:
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todo.emplace_back(steps, loc_, std::move(m_));
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}
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}
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}
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todo.pop_front();
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}
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return std::make_pair(part1,part2);
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}
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} // namespace
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auto main() -> int {
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auto [part1, part2] = Compute(Machine{ParseStream(std::cin)});
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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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