Add 2023 solutions

src/2023/Day11.cpp

@@ -0,0 +1,95 @@
+#include "common/aoc.h"
+
+namespace y2023::day11
+{
+  REGISTER_DAY(2023, Day11, Array2D<char>, int64_t);
+
+  REGISTER_TEST_EXAMPLE(2023, Day11, ExampleInput, 1, 374);
+  REGISTER_TEST(2023, Day11, Input, 1, 9947476);
+  REGISTER_TEST_EXAMPLE(2023, Day11, ExampleInput, 2, 82000210);
+  REGISTER_TEST(2023, Day11, Input, 2, 519939907614);
+
+  READ_INPUT(input)
+  {
+    return Input::ReadArray2D(input);
+  }
+
+  bool IsInbetween(int i1, int i2, int between)
+  {
+    int min = std::min(i1, i2);
+    int max = std::max(i1, i2);
+    return min < between && between < max;
+  }
+
+  int64_t GetSumPairs(const Array2D<char>& input, int expansion)
+  {
+    std::set<int> vertEmpty;
+    std::set<int> horiEmpty;
+    for (int y = 0; y < input.height; y++)
+    {
+      bool empty = true;
+      for (int x = 0; x < input.width; x++)
+      {
+        if (input.Get(x, y) == '#')
+        {
+          empty = false;
+          break;
+        }
+      }
+      if (empty)
+        horiEmpty.emplace(y);
+    }
+    for (int x = 0; x < input.width; x++)
+    {
+      bool empty = true;
+      for (int y = 0; y < input.height; y++)
+      {
+        if (input.Get(x, y) == '#')
+        {
+          empty = false;
+          break;
+        }
+      }
+      if (empty)
+        vertEmpty.emplace(x);
+    }
+    std::vector<Index2D> galaxies;
+    input.Each(
+      [&](const Array2D<char>& map, Index2D index)
+      {
+        if (map.Get(index) == '#')
+          galaxies.emplace_back(index);
+      });
+
+    int64_t sum = 0;
+    for (int i = 0; i < galaxies.size(); i++)
+    {
+      for (int j = i + 1; j < galaxies.size(); j++)
+      {
+        sum += std::abs(galaxies[i].x - galaxies[j].x) + std::abs(galaxies[i].y - galaxies[j].y);
+        for (auto& empty : vertEmpty)
+        {
+          if (IsInbetween(galaxies[i].x, galaxies[j].x, empty))
+            sum += expansion;
+        }
+        for (auto& empty : horiEmpty)
+        {
+          if (IsInbetween(galaxies[i].y, galaxies[j].y, empty))
+            sum += expansion;
+        }
+      }
+    }
+
+    return sum;
+  }
+
+  OUTPUT1(input)
+  {
+    return GetSumPairs(input, 1);
+  }
+
+  OUTPUT2(input)
+  {
+    return GetSumPairs(input, 999999);
+  }
+}