2023 Day 11

2023/puzzle-11-01.cc

@@ -0,0 +1,97 @@
+#include <algorithm>
+#include <cstdint>
+#include <cstdlib>
+#include <iostream>
+#include <string>
+#include <utility>
+#include <vector>
+
+using UInt = std::uint64_t;
+using StringVec = std::vector<std::string>;
+using UIntVec = std::vector<UInt>;
+using Pos = std::pair<UInt, UInt>;
+using PosVec = std::vector<Pos>;
+
+struct StarMap
+{
+  void push_line(std::string const& line)
+  {
+    map_.push_back(line);
+    if (horiz_stars_.size() < line.size()) {
+      horiz_stars_.resize(line.size(), 0);
+    }
+
+    UInt row_count{0};
+    for (auto pos{line.find('#')}; pos != std::string::npos; pos = line.find('#', pos + 1)) {
+      horiz_stars_[pos] += 1;
+      stars_.emplace_back(std::make_pair(pos, vert_stars_.size()));
+      ++row_count;
+    }
+
+    vert_stars_.push_back(row_count);
+  }
+
+  [[nodiscard]] auto star_distances(UInt expansion_coefficient) const -> UInt
+  {
+    UInt size{0};
+    for (auto it1{stars_.begin()}; it1 != stars_.end(); ++it1) {
+      for (auto it2{it1 + 1}; it2 != stars_.end(); ++it2) {
+        size += distance(it1, it2, expansion_coefficient);
+      }
+    }
+
+    return size;
+  }
+
+private:
+  [[nodiscard]] auto distance(PosVec::const_iterator star1, PosVec::const_iterator star2,
+                              UInt expansion_coefficient) const -> UInt
+  {
+    auto [x1, y1] = *star1;
+    auto [x2, y2] = *star2;
+
+    if (x1 > x2) { std::swap(x1, x2); }
+    if (y1 > y2) { std::swap(y1, y2); }
+
+    return (x2 - x1) + (y2 - y1) + expansion_coefficient * (
+             horiz_empty(x1, x2) + vert_empty(y1, y2));
+  }
+
+  [[nodiscard]] auto horiz_empty(UInt x1, UInt x2) const -> UInt
+  {
+    return std::count_if(horiz_stars_.begin() + static_cast<std::int64_t>(x1),
+                         horiz_stars_.begin() + static_cast<std::int64_t>(x2), [](UInt count) {
+                           return count == 0;
+                         });
+  }
+
+  [[nodiscard]] auto vert_empty(UInt x1, UInt x2) const -> UInt
+  {
+    return std::count_if(vert_stars_.begin() + static_cast<std::int64_t>(x1),
+                         vert_stars_.begin() + static_cast<std::int64_t>(x2), [](UInt count) {
+                           return count == 0;
+                         });
+  }
+
+  StringVec map_;
+  UIntVec horiz_stars_;
+  UIntVec vert_stars_;
+  PosVec stars_;
+};
+
+auto main() -> int try {
+  std::string line;
+  StarMap map;
+
+  while (std::getline(std::cin, line)) {
+    map.push_line(line);
+  }
+
+  std::cout << "Star map distance (coeff 1): " << map.star_distances(1) << '\n';
+
+  return EXIT_SUCCESS;;
+}
+catch (...) {
+  std::cerr << "Uncaught exception.\n";
+  return EXIT_FAILURE;
+}

2023/puzzle-11-02.cc

@@ -0,0 +1,100 @@
+#include <algorithm>
+#include <cstdint>
+#include <cstdlib>
+#include <iostream>
+#include <string>
+#include <utility>
+#include <vector>
+
+using UInt = std::uint64_t;
+using StringVec = std::vector<std::string>;
+using UIntVec = std::vector<UInt>;
+using Pos = std::pair<UInt, UInt>;
+using PosVec = std::vector<Pos>;
+
+struct StarMap
+{
+  void push_line(std::string const& line)
+  {
+    map_.push_back(line);
+    if (horiz_stars_.size() < line.size()) {
+      horiz_stars_.resize(line.size(), 0);
+    }
+
+    UInt row_count{0};
+    for (auto pos{line.find('#')}; pos != std::string::npos; pos = line.find('#', pos + 1)) {
+      horiz_stars_[pos] += 1;
+      stars_.emplace_back(std::make_pair(pos, vert_stars_.size()));
+      ++row_count;
+    }
+
+    vert_stars_.push_back(row_count);
+  }
+
+  [[nodiscard]] auto star_distances(UInt expansion_coefficient) const -> UInt
+  {
+    UInt size{0};
+    for (auto it1{stars_.begin()}; it1 != stars_.end(); ++it1) {
+      for (auto it2{it1 + 1}; it2 != stars_.end(); ++it2) {
+        size += distance(it1, it2, expansion_coefficient);
+      }
+    }
+
+    return size;
+  }
+
+private:
+  [[nodiscard]] auto distance(PosVec::const_iterator star1, PosVec::const_iterator star2,
+                              UInt const expansion_coefficient) const -> UInt
+  {
+    auto [x1, y1] = *star1;
+    auto [x2, y2] = *star2;
+
+    if (x1 > x2) { std::swap(x1, x2); }
+    if (y1 > y2) { std::swap(y1, y2); }
+
+    return (x2 - x1) + (y2 - y1) + (expansion_coefficient - 1) * (
+             horiz_empty(x1, x2) + vert_empty(y1, y2));
+  }
+
+  [[nodiscard]] auto horiz_empty(UInt const x1, UInt const x2) const -> UInt
+  {
+    return std::count_if(horiz_stars_.begin() + static_cast<StringVec::difference_type>(x1),
+                         horiz_stars_.begin() + static_cast<StringVec::difference_type>(x2), [](UInt const count) {
+                           return count == 0;
+                         });
+  }
+
+  [[nodiscard]] auto vert_empty(UInt const x1, UInt const x2) const -> UInt
+  {
+    return std::count_if(vert_stars_.begin() + static_cast<StringVec::difference_type>(x1),
+                         vert_stars_.begin() + static_cast<StringVec::difference_type>(x2), [](UInt const count) {
+                           return count == 0;
+                         });
+  }
+
+  StringVec map_;
+  UIntVec horiz_stars_;
+  UIntVec vert_stars_;
+  PosVec stars_;
+};
+
+auto main() -> int try {
+  std::string line;
+  StarMap map;
+
+  while (std::getline(std::cin, line)) {
+    map.push_line(line);
+  }
+
+  std::cout << "Star map distance (coeff 2): " << map.star_distances(2) << '\n';
+  std::cout << "Star map distance (coeff 10): " << map.star_distances(10) << '\n';
+  std::cout << "Star map distance (coeff 100): " << map.star_distances(100) << '\n';
+  std::cout << "Star map distance (coeff 1000000): " << map.star_distances(1000000) << '\n';
+
+  return EXIT_SUCCESS;;
+}
+catch (...) {
+  std::cerr << "Uncaught exception.\n";
+  return EXIT_FAILURE;
+}