Initial commit with solutions from 2024

src/2024/Day18.cpp

@@ -0,0 +1,96 @@
+#include "common/aoc.h"
+
+namespace day18
+{
+  using Memory = std::map<Index2D, int>;
+  REGISTER_DAY(2024, Day18, Memory, int32_t);
+
+  REGISTER_TEST_EXAMPLE(2024, Day18, ExampleInput, 1, 22);
+  REGISTER_TEST(2024, Day18, Input, 1, 304);
+  REGISTER_TEST_EXAMPLE(2024, Day18, ExampleInput, 2, 20);
+  REGISTER_TEST(2024, Day18, Input, 2, 2876);
+
+  READ_INPUT(input)
+  {
+    std::map<Index2D, int> memory;
+    std::string str;
+    int i = 0;
+    while (std::getline(input, str))
+    {
+      Index2D index;
+      std::stringstream ss{str};
+      ss >> index.x >> "," >> index.y;
+      memory.emplace(index, i);
+      i++;
+    }
+    return memory;
+  }
+
+  struct Map
+  {
+    const std::map<Index2D, int>& memory;
+    int size;
+    int time;
+  };
+
+  std::vector<std::pair<int, Index2D>> Branch(const Map& map, const Index2D& current)
+  {
+    std::vector<std::pair<int, Index2D>> branch;
+    for (auto& dir : Helper::GetNeighborDirections())
+    {
+      Index2D pos = current + dir;
+      if (pos.x < 0 || pos.y < 0 || pos.x > map.size || pos.y > map.size)
+        continue;
+      auto it = map.memory.find(pos);
+      if (it == map.memory.end() || it->second >= map.time)
+        branch.emplace_back(1, pos);
+    }
+    return branch;
+  }
+
+  bool Goal(const Map& map, const Index2D& current)
+  {
+    return current.x == map.size && current.y == map.size;
+  }
+
+  bool ValidPath(const Map& map, int index)
+  {
+    Map cpy = map;
+    cpy.time = index;
+    return Helper::Dijkstras(cpy, Index2D{0, 0}, Branch, Goal) != 0;
+  }
+
+  OUTPUT1(input)
+  {
+    int32_t sum = 0;
+    int time = 1024;
+    int size = 70;
+    if (isExample)
+    {
+      size = 6;
+      time = 12;
+    }
+    Map map{input, size, time};
+    return Helper::Dijkstras(map, Index2D{0, 0}, Branch, Goal);
+  }
+
+  OUTPUT2(input)
+  {
+    int size = 70;
+    if (isExample)
+      size = 6;
+
+    Map map{input, size, 0};
+    int result = Helper::BinarySearch(map, 0, input.size(), ValidPath);
+    for (auto& index : input)
+    {
+      if (index.second == result)
+      {
+        std::cout << index.first.x << "," << index.first.y << std::endl;
+        return result;
+      }
+    }
+
+    return 0;
+  }
+}