Add 2016 day 13 puzzles

2016/puzzle-13-01.cc

@@ -0,0 +1,115 @@
+//
+// Created by Matthew Gretton-Dann on 06/12/2021.
+//
+
+#include <iostream>
+#include <set>
+#include <string>
+
+using Num = unsigned long;
+
+struct Node
+{
+  Node(Num x, Num y, Num cost) : x_(x), y_(y), cost_(cost) {}
+
+  auto operator==(Node const& rhs) const noexcept -> bool { return x_ == rhs.x_ && y_ == rhs.y_; }
+
+  auto operator<(Node const& rhs) const noexcept -> bool
+  {
+    return x_ < rhs.x_ || (x_ == rhs.x_ && y_ < rhs.y_);
+  }
+
+  Num x() const noexcept { return x_; }
+  Num y() const noexcept { return y_; }
+  Num cost() const noexcept { return cost_; }
+
+  Node move_left() { return {x_ - 1, y_, cost_ + 1}; }
+  Node move_up() { return {x_, y_ + 1, cost_ + 1}; }
+  Node move_right() { return {x_ + 1, y_, cost_ + 1}; }
+  Node move_down() { return {x_, y_ - 1, cost_ + 1}; }
+
+private:
+  Num x_;
+  Num y_;
+  Num cost_;
+};
+
+auto is_wall(Num num, Node const& node)
+{
+  Num value{num + node.x() * node.x() + 3 * node.x() + 2 * node.x() * node.y() + node.y() +
+            node.y() * node.y()};
+  Num bit_count{0};
+  while (value != 0) {
+    bit_count += value & 1;
+    value >>= 1;
+  }
+  return ((bit_count & 1) == 1) ? true : false;
+}
+
+struct CostCompare
+{
+  constexpr auto operator()(Node const& lhs, Node const& rhs) const noexcept -> bool
+  {
+    return lhs.cost() < rhs.cost();
+  }
+};
+
+using ToVisitSet = std::multiset<Node, CostCompare>;
+using VisitedSet = std::set<Node>;
+
+void update_to_visit(ToVisitSet& to_visit, VisitedSet const& visited, Num key, Node const& n)
+{
+  if (is_wall(key, n)) {
+    return;
+  }
+
+  if (visited.contains(n)) {
+    return;
+  }
+
+  auto it{std::find(to_visit.begin(), to_visit.end(), n)};
+  if (it == to_visit.end()) {
+    to_visit.insert(n);
+  }
+  else if (n.cost() < it->cost()) {
+    to_visit.erase(it);
+    to_visit.insert(n);
+  }
+}
+
+auto main() -> int
+{
+  VisitedSet visited;
+  ToVisitSet to_visit;
+
+  std::string line;
+  if (!std::getline(std::cin, line)) {
+    std::cerr << "Unable to read line.\n";
+    return 1;
+  }
+  Num key{std::stoul(line)};
+
+  to_visit.insert(Node{1, 1, 0});
+  while (!to_visit.empty()) {
+    auto it{to_visit.begin()};
+    Node n(*it);
+    if (n.x() == 31 && n.y() == 39) {
+      std::cout << "Cost = " << n.cost();
+      return 0;
+    }
+
+    to_visit.erase(it);
+    visited.insert(n);
+    if (n.x() > 0) {
+      update_to_visit(to_visit, visited, key, n.move_left());
+    }
+    if (n.y() > 0) {
+      update_to_visit(to_visit, visited, key, n.move_down());
+    }
+    update_to_visit(to_visit, visited, key, n.move_right());
+    update_to_visit(to_visit, visited, key, n.move_up());
+  }
+
+  std::cout << "No solution.\n";
+  return 1;
+}

2016/puzzle-13-02.cc

@@ -0,0 +1,115 @@
+//
+// Created by Matthew Gretton-Dann on 06/12/2021.
+//
+
+#include <iostream>
+#include <set>
+#include <string>
+
+using Num = unsigned long;
+
+struct Node
+{
+  Node(Num x, Num y, Num cost) : x_(x), y_(y), cost_(cost) {}
+
+  auto operator==(Node const& rhs) const noexcept -> bool { return x_ == rhs.x_ && y_ == rhs.y_; }
+
+  auto operator<(Node const& rhs) const noexcept -> bool
+  {
+    return x_ < rhs.x_ || (x_ == rhs.x_ && y_ < rhs.y_);
+  }
+
+  Num x() const noexcept { return x_; }
+  Num y() const noexcept { return y_; }
+  Num cost() const noexcept { return cost_; }
+
+  Node move_left() { return {x_ - 1, y_, cost_ + 1}; }
+  Node move_up() { return {x_, y_ + 1, cost_ + 1}; }
+  Node move_right() { return {x_ + 1, y_, cost_ + 1}; }
+  Node move_down() { return {x_, y_ - 1, cost_ + 1}; }
+
+private:
+  Num x_;
+  Num y_;
+  Num cost_;
+};
+
+auto is_wall(Num num, Node const& node)
+{
+  Num value{num + node.x() * node.x() + 3 * node.x() + 2 * node.x() * node.y() + node.y() +
+            node.y() * node.y()};
+  Num bit_count{0};
+  while (value != 0) {
+    bit_count += value & 1;
+    value >>= 1;
+  }
+  return ((bit_count & 1) == 1) ? true : false;
+}
+
+struct CostCompare
+{
+  constexpr auto operator()(Node const& lhs, Node const& rhs) const noexcept -> bool
+  {
+    return lhs.cost() < rhs.cost();
+  }
+};
+
+using ToVisitSet = std::multiset<Node, CostCompare>;
+using VisitedSet = std::set<Node>;
+
+void update_to_visit(ToVisitSet& to_visit, VisitedSet const& visited, Num key, Node const& n)
+{
+  if (is_wall(key, n)) {
+    return;
+  }
+
+  if (visited.contains(n)) {
+    return;
+  }
+
+  if (n.cost() > 50) {
+    return;
+  }
+
+  auto it{std::find(to_visit.begin(), to_visit.end(), n)};
+  if (it == to_visit.end()) {
+    to_visit.insert(n);
+  }
+  else if (n.cost() < it->cost()) {
+    to_visit.erase(it);
+    to_visit.insert(n);
+  }
+}
+
+auto main() -> int
+{
+  VisitedSet visited;
+  ToVisitSet to_visit;
+
+  std::string line;
+  if (!std::getline(std::cin, line)) {
+    std::cerr << "Unable to read line.\n";
+    return 1;
+  }
+  Num key{std::stoul(line)};
+
+  to_visit.insert(Node{1, 1, 0});
+  while (!to_visit.empty()) {
+    auto it{to_visit.begin()};
+    Node n(*it);
+
+    to_visit.erase(it);
+    visited.insert(n);
+    if (n.x() > 0) {
+      update_to_visit(to_visit, visited, key, n.move_left());
+    }
+    if (n.y() > 0) {
+      update_to_visit(to_visit, visited, key, n.move_down());
+    }
+    update_to_visit(to_visit, visited, key, n.move_right());
+    update_to_visit(to_visit, visited, key, n.move_up());
+  }
+
+  std::cout << "Number of visited locations: " << visited.size() << '\n';
+  return 0;
+}