Add 2016 day 24 puzzles

2016/puzzle-24-01.cc

@@ -0,0 +1,99 @@
+#include <iostream>
+#include <map>
+#include <set>
+#include <string>
+#include <vector>
+
+using Int = unsigned;
+using Coord = std::pair<Int, Int>;
+using Map = std::vector<std::string>;
+using PointMap = std::map<char, Coord>;
+using PointCostMap = std::multimap<char, std::pair<char, Int>>;
+
+void update_cost_map(PointCostMap& cost_map, Map const& map, std::pair<char, Coord> start)
+{
+  std::set<Coord> visited;
+  std::set<Coord> to_visit;
+  to_visit.insert(start.second);
+
+  Int cost{0};
+  while (!to_visit.empty()) {
+    visited.insert(to_visit.begin(), to_visit.end());
+    std::set<Coord> next_to_visit;
+    for (auto const& n : to_visit) {
+      char c{map[n.second][n.first]};
+      if (c == '#') {
+        abort();
+      }
+
+      if (c != '.') {
+        cost_map.insert({start.first, {c, cost}});
+      }
+
+      auto add = [&map, &visited, &next_to_visit](Int x, Int y) {
+        if (map[y][x] != '#' && !visited.contains(Coord{x, y})) {
+          next_to_visit.insert(Coord{x, y});
+        }
+      };
+      add(n.first, n.second - 1);
+      add(n.first, n.second + 1);
+      add(n.first - 1, n.second);
+      add(n.first + 1, n.second);
+    }
+    ++cost;
+    std::swap(to_visit, next_to_visit);
+  }
+}
+
+auto find_lowest_cost(PointCostMap const& cost_map, std::size_t point_count)
+  -> std::pair<std::string, Int>
+{
+  std::multimap<Int, std::string> nodes;
+  nodes.insert({0, "0"});
+
+  while (!nodes.empty()) {
+    auto it{nodes.begin()};
+    Int cost{it->first};
+    std::string visited{it->second};
+    if (visited.size() == point_count) {
+      return {visited, cost};
+    }
+    nodes.erase(it);
+
+    auto [cm_begin, cm_end] = cost_map.equal_range(visited[visited.size() - 1]);
+    for (auto cm_it{cm_begin}; cm_it != cm_end; ++cm_it) {
+      if (visited.find(cm_it->second.first) == std::string::npos) {
+        nodes.insert({cost + cm_it->second.second, visited + cm_it->second.first});
+      }
+    }
+  }
+
+  abort();
+}
+
+auto main() -> int
+{
+  Map map;
+  PointMap points;
+  std::string line;
+
+  // Read in map and find the locations we want to visit.
+  while (std::getline(std::cin, line) && !line.empty()) {
+    auto y{map.size()};
+    map.push_back(line);
+    std::size_t x{0};
+    for (x = line.find_first_not_of(".#", x); x != std::string::npos;
+         x = line.find_first_not_of(".#", x + 1)) {
+      points.insert({line[x], {x, y}});
+    }
+  }
+
+  PointCostMap cost_map;
+  for (auto const& p : points) {
+    update_cost_map(cost_map, map, p);
+  }
+
+  auto [route, cost] = find_lowest_cost(cost_map, points.size());
+  std::cout << "Route: " << route << " costs " << cost << '\n';
+  return 0;
+}

2016/puzzle-24-02.cc

@@ -0,0 +1,102 @@
+#include <iostream>
+#include <map>
+#include <set>
+#include <string>
+#include <vector>
+
+using Int = unsigned;
+using Coord = std::pair<Int, Int>;
+using Map = std::vector<std::string>;
+using PointMap = std::map<char, Coord>;
+using PointCostMap = std::multimap<char, std::pair<char, Int>>;
+
+void update_cost_map(PointCostMap& cost_map, Map const& map, std::pair<char, Coord> start)
+{
+  std::set<Coord> visited;
+  std::set<Coord> to_visit;
+  to_visit.insert(start.second);
+
+  Int cost{0};
+  while (!to_visit.empty()) {
+    visited.insert(to_visit.begin(), to_visit.end());
+    std::set<Coord> next_to_visit;
+    for (auto const& n : to_visit) {
+      char c{map[n.second][n.first]};
+      if (c == '#') {
+        abort();
+      }
+
+      if (c != '.') {
+        cost_map.insert({start.first, {c, cost}});
+      }
+
+      auto add = [&map, &visited, &next_to_visit](Int x, Int y) {
+        if (map[y][x] != '#' && !visited.contains(Coord{x, y})) {
+          next_to_visit.insert(Coord{x, y});
+        }
+      };
+      add(n.first, n.second - 1);
+      add(n.first, n.second + 1);
+      add(n.first - 1, n.second);
+      add(n.first + 1, n.second);
+    }
+    ++cost;
+    std::swap(to_visit, next_to_visit);
+  }
+}
+
+auto find_lowest_cost(PointCostMap const& cost_map, std::size_t point_count)
+  -> std::pair<std::string, Int>
+{
+  std::multimap<Int, std::string> nodes;
+  nodes.insert({0, "0"});
+
+  while (!nodes.empty()) {
+    auto it{nodes.begin()};
+    Int cost{it->first};
+    std::string visited{it->second};
+    if (visited.size() == point_count + 1) {
+      return {visited, cost};
+    }
+    nodes.erase(it);
+
+    auto [cm_begin, cm_end] = cost_map.equal_range(visited[visited.size() - 1]);
+    for (auto cm_it{cm_begin}; cm_it != cm_end; ++cm_it) {
+      if (visited.find(cm_it->second.first) == std::string::npos) {
+        nodes.insert({cost + cm_it->second.second, visited + cm_it->second.first});
+      }
+      if (cm_it->second.first == '0' && visited.size() == point_count) {
+        nodes.insert({cost + cm_it->second.second, visited + cm_it->second.first});
+      }
+    }
+  }
+
+  abort();
+}
+
+auto main() -> int
+{
+  Map map;
+  PointMap points;
+  std::string line;
+
+  // Read in map and find the locations we want to visit.
+  while (std::getline(std::cin, line) && !line.empty()) {
+    auto y{map.size()};
+    map.push_back(line);
+    std::size_t x{0};
+    for (x = line.find_first_not_of(".#", x); x != std::string::npos;
+         x = line.find_first_not_of(".#", x + 1)) {
+      points.insert({line[x], {x, y}});
+    }
+  }
+
+  PointCostMap cost_map;
+  for (auto const& p : points) {
+    update_cost_map(cost_map, map, p);
+  }
+
+  auto [route, cost] = find_lowest_cost(cost_map, points.size());
+  std::cout << "Route: " << route << " costs " << cost << '\n';
+  return 0;
+}