Add 2021 solutions

src/2021/Day04.cpp

@@ -0,0 +1,127 @@
+#include "common/aoc.h"
+
+namespace y2021::day04
+{
+  struct Game
+  {
+    std::vector<int> input;
+    std::vector<Array2D<int>> boards;
+  };
+
+  bool MarkAndCheck(Array2D<int>& board, int number)
+  {
+    Index2D index = board.Find(number);
+    if (index)
+    {
+      board[index] = -1;
+      // Check board is filled
+      bool filledX = true;
+      bool filledY = true;
+      for (int i = 0; i < 5; i++)
+      {
+        if (board.Get(i, index.y) != -1)
+          filledX = false;
+        if (board.Get(index.x, i) != -1)
+          filledY = false;
+      }
+      return filledX || filledY;
+    }
+    return false;
+  }
+
+  REGISTER_DAY(2021, Day04, Game, int);
+
+  REGISTER_TEST_EXAMPLE(2021, Day04, ExampleInput, 1, 4512);
+  REGISTER_TEST(2021, Day04, Input, 1, 54275);
+  REGISTER_TEST_EXAMPLE(2021, Day04, ExampleInput, 2, 1924);
+  REGISTER_TEST(2021, Day04, Input, 2, 13158);
+
+  READ_INPUT(input)
+  {
+    Game game;
+    std::string str;
+    getline(input, str);
+    std::stringstream ss{str};
+    while (getline(ss, str, ','))
+    {
+      game.input.emplace_back(atoi(str.c_str()));
+    }
+    getline(input, str);
+    while (!input.eof())
+    {
+      Array2D<int> array2D{5, 5};
+      for (int y = 0; y < 5; y++)
+      {
+        getline(input, str);
+        std::stringstream ss{str};
+        for (int x = 0; x < 5; x++)
+        {
+          int i;
+          ss >> i;
+          array2D.Set(x, y, i);
+        }
+      }
+      game.boards.emplace_back(array2D);
+      getline(input, str);
+    }
+    return game;
+  }
+
+  OUTPUT1(input)
+  {
+    Game game = input;  // Copy the data to be able to modify it
+    int winner = -1;
+    int i = 0;
+    while (winner == -1)
+    {
+      int number = game.input[i];
+      for (auto& board : game.boards)
+      {
+        if (MarkAndCheck(board, number))
+        {
+          int total = 0;
+          for (auto& val : board)
+          {
+            if (val != -1)
+              total += val;
+          }
+          return total * number;
+        }
+      }
+      i++;
+    }
+    return 0;
+  }
+
+  OUTPUT2(input)
+  {
+    Game game = input;  // Copy the data to be able to modify it
+    int winner = -1;
+    int i = 0;
+    while (winner == -1)
+    {
+      int number = game.input[i];
+      for (auto it = game.boards.begin(); it != game.boards.end();)
+      {
+        if (MarkAndCheck(*it, number))
+        {
+          if (game.boards.size() == 1)
+          {
+            int total = 0;
+            for (auto& val : game.boards.front())
+            {
+              if (val != -1)
+                total += val;
+            }
+            return total * number;
+          }
+          it = game.boards.erase(it);
+        }
+        else
+          it++;
+      }
+      i++;
+    }
+    return 0;
+  }
+}