Add Puzzles for 2022 day 12

2022/puzzle-12-02.cc

@@ -0,0 +1,116 @@
+#include <array>
+#include <functional>
+#include <iostream>
+#include <string>
+#include <vector>
+
+#include "graph-utils.h"
+
+using Int = std::int64_t;
+
+struct Pos
+{
+  Pos() noexcept = default;
+  Pos(Int x, Int y) noexcept : x_(x), y_(y) {}
+  Pos(Pos const&) noexcept = default;
+  auto operator=(Pos const&) noexcept -> Pos& = default;
+  Pos(Pos&&) noexcept = default;
+  auto operator=(Pos&&) noexcept -> Pos& = default;
+  ~Pos() noexcept = default;
+
+  [[nodiscard]] auto x() const { return x_; }
+  [[nodiscard]] auto y() const { return y_; }
+
+private:
+  Int x_{0};
+  Int y_{0};
+};
+
+auto operator+(Pos const& x, Pos const& y) noexcept -> Pos
+{
+  return Pos{x.x() + y.x(), x.y() + y.y()};
+}
+
+auto operator<(Pos const& l, Pos const& r) noexcept -> bool
+{
+  return l.y() < r.y() || (l.y() == r.y() && l.x() < r.x());
+}
+
+auto operator==(Pos const& l, Pos const& r) noexcept -> bool
+{
+  return l.x() == r.x() && l.y() == r.y();
+}
+
+using Height = char;
+
+struct Map
+{
+  explicit Map(std::istream& is)
+  {
+    std::string line;
+    while (std::getline(is, line)) {
+      auto s = line.find('S');
+      if (s != std::string::npos) {
+        start_ = Pos{static_cast<Int>(s), static_cast<Int>(rows_.size())};
+        line[s] = 'a';
+      }
+      auto e = line.find('E');
+      if (e != std::string::npos) {
+        end_ = Pos{static_cast<Int>(e), static_cast<Int>(rows_.size())};
+        line[e] = 'z';
+      }
+      rows_.push_back(line);
+    }
+  }
+  [[nodiscard]] auto start() const -> Pos { return start_; }
+  [[nodiscard]] auto end() const -> Pos { return end_; }
+  [[nodiscard]] auto width() const -> Int { return static_cast<Int>(rows_[0].length()); }
+  [[nodiscard]] auto depth() const -> Int { return static_cast<Int>(rows_.size()); }
+  [[nodiscard]] auto height(Pos const& p) const -> Height
+  {
+    return rows_[p.y()][p.x()];
+  }
+
+private:
+  std::vector<std::string> rows_;
+  Pos start_{0, 0};
+  Pos end_{0, 0};
+};
+
+struct StateTranstitionManager
+{
+  explicit StateTranstitionManager(Map map) : map_(std::move(map)) {}
+
+  Map map_;
+
+  [[nodiscard]] auto is_finished(Pos const& pos) const -> bool { return map_.height(pos) == 'a'; }
+
+  template<typename Inserter>
+  void generate_children(Pos const& current, Inserter inserter) const
+  {
+    std::array<Pos, 4> const moves{Pos{0, 1}, Pos{0, -1}, Pos{1, 0}, Pos{-1, 0}};
+    for (auto const& move : moves) {
+      auto pos{current + move};
+      // Check in bounds
+      if (pos.x() < 0 || pos.x() > map_.width() || pos.y() < 0 || pos.y() > map_.depth()) {
+        continue;
+      }
+      // check height hasn't changed too far
+      if (map_.height(pos) < map_.height(current) - 1) {
+        continue;
+      }
+      inserter(pos, 1);
+    }
+  }
+};
+
+auto main() -> int
+{
+  Map const map(std::cin);
+  Pos const initial_state{map.end()};
+
+  auto [finished_state, finished_cost] =
+    dijkstra(initial_state, Int{0}, StateTranstitionManager{map});
+  std::cout << "Done with cost " << finished_cost << '\n';
+  return 0;
+}