96 lines
2.1 KiB
C++
96 lines
2.1 KiB
C++
#include <iostream>
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#include <set>
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#include <string>
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#include <vector>
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using Int = long;
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using Coord = std::pair<Int, Int>;
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struct State
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{
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explicit State(std::vector<std::string> const& initial_state)
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{
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Coord pos{0, 0};
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for (auto const& line : initial_state) {
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pos.first = 0;
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for (auto c : line) {
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if (c == '#') {
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infected_.insert(pos);
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}
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++pos.first;
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}
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++pos.second;
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}
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pos_ = Coord{pos.first / 2, pos.second / 2};
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}
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void burst()
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{
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if (infected_.contains(pos_)) {
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dir_ = Coord{-dir_.second, dir_.first};
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infected_.erase(pos_);
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}
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else {
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dir_ = Coord{dir_.second, -dir_.first};
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infected_.insert(pos_);
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++activity_;
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}
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pos_ = Coord{pos_.first + dir_.first, pos_.second + dir_.second};
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}
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[[nodiscard]] auto activity() const -> std::size_t { return activity_; }
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void print() const
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{
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Int xmin{std::numeric_limits<Int>::max()};
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Int xmax{std::numeric_limits<Int>::min()};
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Int ymin{std::numeric_limits<Int>::max()};
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Int ymax{std::numeric_limits<Int>::min()};
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for (auto const& c : infected_) {
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xmin = std::min(c.first, xmin);
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xmax = std::max(c.first, xmax);
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ymin = std::min(c.second, ymin);
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ymax = std::max(c.second, ymax);
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}
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for (auto y{ymin}; y <= ymax; ++y) {
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for (auto x{xmin}; x <= xmax; ++x) {
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Coord pos{x, y};
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bool infected{infected_.contains(pos)};
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if (pos == pos_) {
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std::cout << (infected ? '*' : '_');
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}
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else {
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std::cout << (infected ? '#' : '.');
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}
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}
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std::cout << '\n';
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}
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}
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private:
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std::set<Coord> infected_;
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Coord pos_;
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Coord dir_{0, -1};
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Int activity_{0};
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};
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auto main() -> int
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{
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std::vector<std::string> initial;
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std::string line;
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while (std::getline(std::cin, line) && !line.empty()) {
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initial.push_back(line);
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}
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State state(initial);
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constexpr unsigned count{10'000};
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for (unsigned i{0}; i < count; ++i) {
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state.burst();
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}
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std::cout << "Number of new infections: " << state.activity() << '\n';
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return 0;
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}
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