day 4 part 1

src/2024/CMakeLists.txt

@@ -14,6 +14,7 @@ add_subdirectory(lib)
 create_standard_test(NAME 2024_day1 SOURCES day1.cpp LIBRARIES aoc2024 YEAR 2024)
 create_standard_test(NAME 2024_day2 SOURCES day2.cpp LIBRARIES aoc2024 YEAR 2024)
 create_standard_test(NAME 2024_day3 SOURCES day3.cpp LIBRARIES aoc2024 YEAR 2024)
+create_standard_test(NAME 2024_day4 SOURCES day4.cpp LIBRARIES aoc2024 YEAR 2024)
 
 ################################################################################
 # Copy input data

src/2024/day4.cpp

@@ -0,0 +1,148 @@
+#include <iostream>
+#include <filesystem>
+#include <fstream>
+#include <string>
+#include <vector>
+#include <benchmark/benchmark.h>
+
+struct Data {
+  std::vector<std::string> grid;
+};
+
+int check(const std::string& s) {
+  if (s.size() == 4 && s == "XMAS") {
+    return 1;
+  }
+  return 0;
+}
+
+int part1(const Data &data)
+{
+  size_t width = data.grid[0].size();
+  size_t height = data.grid.size();
+  int count = 0;
+
+  for(size_t y = 0; y < data.grid.size(); ++y) {
+    for(size_t x = 0; x < data.grid[0].size(); ++x) {
+      // look forward
+      if (width - x >= 4) {
+        count += check(data.grid[y].substr(x, 4));
+      }
+      // look backward
+      if (x >= 3) {
+        std::string s = {data.grid[y][x], data.grid[y][x-1], data.grid[y][x-2], data.grid[y][x-3]};
+        count += check(s);
+      }
+      // look along negative x diagonal forward
+      if (height-y >= 4 && width-x >= 4) {
+        std::string s = {data.grid[y][x], data.grid[y+1][x+1], data.grid[y+2][x+2], data.grid[y+3][x+3]};
+        count += check(s);
+      }
+      // look along negative x diagonal backward
+      if (y >= 3 && x >= 3) {
+        std::string s = {data.grid[y][x], data.grid[y-1][x-1], data.grid[y-2][x-2], data.grid[y-3][x-3]};
+        count += check(s);
+      }
+      // look along positive x diagonal forward
+      if (y >= 3 && width - x >= 4) {
+        std::string s = {data.grid[y][x], data.grid[y-1][x+1], data.grid[y-2][x+2], data.grid[y-3][x+3]};
+        count += check(s);
+      }
+      // look along positive x diagonal backward
+      if (height - y >= 4 && x >= 3) {
+        std::string s = {data.grid[y][x], data.grid[y+1][x-1], data.grid[y+2][x-2], data.grid[y+3][x-3]};
+        count += check(s);
+      }
+      // look up
+      if (y >= 3) {
+        std::string s = {data.grid[y][x], data.grid[y-1][x], data.grid[y-2][x], data.grid[y-3][x]};
+        count += check(s);
+      }
+      // look down
+      if (height - y >= 4) {
+        std::string s = {data.grid[y][x], data.grid[y+1][x], data.grid[y+2][x], data.grid[y+3][x]};
+        count += check(s);
+      }
+    }
+  }
+  return count;
+}
+
+int part2(const Data &data)
+{
+  return 0;
+}
+
+Data parse()
+{
+  std::ifstream file(std::filesystem::path("inputs/day4.txt"));
+  if (!file.is_open())
+  {
+    throw std::runtime_error("file not found");
+  }
+  std::string line;
+  Data data;
+
+  while (std::getline(file, line))
+  {
+    data.grid.push_back(line);
+  }
+
+  return data;
+}
+
+class BenchmarkFixture : public benchmark::Fixture
+{
+public:
+  static Data data;
+};
+
+Data BenchmarkFixture::data = parse();
+
+BENCHMARK_DEFINE_F(BenchmarkFixture, Part1Benchmark)
+(benchmark::State &state)
+{
+  for (auto _ : state)
+  {
+    int s = part1(data);
+    benchmark::DoNotOptimize(s);
+  }
+}
+
+BENCHMARK_DEFINE_F(BenchmarkFixture, Part2Benchmark)
+(benchmark::State &state)
+{
+  for (auto _ : state)
+  {
+    int s = part2(data);
+    benchmark::DoNotOptimize(s);
+  }
+}
+
+BENCHMARK_REGISTER_F(BenchmarkFixture, Part1Benchmark);
+BENCHMARK_REGISTER_F(BenchmarkFixture, Part2Benchmark);
+
+int main(int argc, char **argv)
+{
+  Data data = parse();
+
+  int answer1 = 0;
+  int answer2 = 0;
+
+  auto first = part1(data);
+  auto second = part2(data);
+
+  std::cout << "Part 1: " << first << std::endl;
+  std::cout << "Part 2: " << second << std::endl;
+
+  first != answer1 ? throw std::runtime_error("Part 1 incorrect") : nullptr;
+  second != answer2 ? throw std::runtime_error("Part 2 incorrect") : nullptr;
+
+  for (int i = 1; i < argc; ++i) {
+    if (std::string(argv[i]) == "--benchmark") {
+      benchmark::Initialize(&argc, argv);
+      benchmark::RunSpecifiedBenchmarks();
+      return 0;
+    }
+  }
+}