Add 2017 Day 22 puzzles

2017/puzzle-22-01.cc

@@ -0,0 +1,95 @@
+#include <iostream>
+#include <set>
+#include <string>
+#include <vector>
+
+using Int = long;
+using Coord = std::pair<Int, Int>;
+
+struct State
+{
+  explicit State(std::vector<std::string> const& initial_state)
+  {
+    Coord pos{0, 0};
+    for (auto const& line : initial_state) {
+      pos.first = 0;
+      for (auto c : line) {
+        if (c == '#') {
+          infected_.insert(pos);
+        }
+        ++pos.first;
+      }
+      ++pos.second;
+    }
+    pos_ = Coord{pos.first / 2, pos.second / 2};
+  }
+
+  void burst()
+  {
+    if (infected_.contains(pos_)) {
+      dir_ = Coord{-dir_.second, dir_.first};
+      infected_.erase(pos_);
+    }
+    else {
+      dir_ = Coord{dir_.second, -dir_.first};
+      infected_.insert(pos_);
+      ++activity_;
+    }
+    pos_ = Coord{pos_.first + dir_.first, pos_.second + dir_.second};
+  }
+
+  [[nodiscard]] auto activity() const -> std::size_t { return activity_; }
+
+  void print() const
+  {
+    Int xmin{std::numeric_limits<Int>::max()};
+    Int xmax{std::numeric_limits<Int>::min()};
+    Int ymin{std::numeric_limits<Int>::max()};
+    Int ymax{std::numeric_limits<Int>::min()};
+    for (auto const& c : infected_) {
+      xmin = std::min(c.first, xmin);
+      xmax = std::max(c.first, xmax);
+      ymin = std::min(c.second, ymin);
+      ymax = std::max(c.second, ymax);
+    }
+
+    for (auto y{ymin}; y <= ymax; ++y) {
+      for (auto x{xmin}; x <= xmax; ++x) {
+        Coord pos{x, y};
+        bool infected{infected_.contains(pos)};
+        if (pos == pos_) {
+          std::cout << (infected ? '*' : '_');
+        }
+        else {
+          std::cout << (infected ? '#' : '.');
+        }
+      }
+      std::cout << '\n';
+    }
+  }
+
+private:
+  std::set<Coord> infected_;
+  Coord pos_;
+  Coord dir_{0, -1};
+  Int activity_{0};
+};
+
+auto main() -> int
+{
+  std::vector<std::string> initial;
+  std::string line;
+  while (std::getline(std::cin, line) && !line.empty()) {
+    initial.push_back(line);
+  }
+
+  State state(initial);
+
+  constexpr unsigned count{10'000};
+  for (unsigned i{0}; i < count; ++i) {
+    state.burst();
+  }
+
+  std::cout << "Number of new infections: " << state.activity() << '\n';
+  return 0;
+}