Solve day 4 part 1

day_4.cpp

@@ -0,0 +1,52 @@
+#include <fstream>
+#include <iostream>
+#include <vector>
+
+struct position
+{
+	int x;
+	int y;
+};
+
+int main()
+{
+	std::ifstream file("input.txt");
+
+	std::vector<std::string> lines;
+	std::string line;
+	while (getline(file, line)) lines.push_back(line);
+
+	const position positions[] = {
+		{ -1, -1 },
+		{ 0, -1 },
+		{ 1, -1 },
+		{ -1, 0 },
+		{ 1, 0 },
+		{ -1, 1 },
+		{ 0, 1 },
+		{ 1, 1 },
+	};
+
+	int result = 0;
+
+	for (int y = 0; y < lines.size(); y++) {
+		for (int x = 0; x < lines[y].size(); x++) {
+			if (lines[y][x] == '.') continue;
+
+			int amount = 0;
+
+			for (position pos : positions) {
+				int check_x = x + pos.x, check_y = y + pos.y;
+
+				if (check_x < 0 || check_y < 0 || check_x >= lines[y].size() || check_y >= line.size())
+					continue;
+
+				if (lines[check_y][check_x] == '@') amount++;
+			}
+
+			if (amount < 4) result++;
+		}
+	}
+
+	std::cout << result << std::endl;
+}