AOC2023: implement day2

userspace/aoc2023/day2/CMakeLists.txt

@@ -0,0 +1,22 @@
+cmake_minimum_required(VERSION 3.26)
+
+project(aoc2023_day2 CXX)
+
+set(SOURCES
+	main.cpp
+)
+
+add_executable(aoc2023_day2 ${SOURCES})
+target_compile_options(aoc2023_day2 PUBLIC -O2 -g)
+target_link_libraries(aoc2023_day2 PUBLIC libc)
+
+add_dependencies(aoc2023_day2 libc-install ban-install)
+
+add_custom_target(aoc2023_day2-install
+	COMMAND ${CMAKE_COMMAND} -E copy ${CMAKE_CURRENT_BINARY_DIR}/aoc2023_day2 ${BANAN_AOC2023_BIN}/day2
+	DEPENDS aoc2023_day2
+	DEPENDS aoc2023_always
+)
+
+add_dependencies(aoc2023 aoc2023_day2)
+add_dependencies(aoc2023-install aoc2023_day2-install)

userspace/aoc2023/day2/main.cpp

@@ -0,0 +1,116 @@
+#include <ctype.h>
+#include <stdio.h>
+#include <string.h>
+
+#define MAX(a, b) ((a) < (b)) ? (b) : (a)
+
+int parse_int_and_advance(const char*& ptr)
+{
+	int result = 0;
+	while (isdigit(*ptr))
+		result = (result * 10) + (*ptr++ - '0');
+	return result;
+}
+
+int puzzle1(FILE* fp)
+{
+	int result = 0;
+
+	char buffer[256];
+	while (fgets(buffer, sizeof(buffer), fp))
+	{
+		const char* ptr = buffer;
+
+		if (strncmp("Game ", ptr, 5))
+			continue;
+		ptr += 5;
+	
+		int id = parse_int_and_advance(ptr);
+		ptr += 2;
+
+		bool valid = true;
+		while (*ptr && valid)
+		{
+			int count = parse_int_and_advance(ptr);
+
+			ptr++;
+			if (strncmp(ptr, "red", 3) == 0)
+				valid = (count <= 12);
+			if (strncmp(ptr, "green", 5) == 0)
+				valid = (count <= 13);
+			if (strncmp(ptr, "blue", 4) == 0)
+				valid = (count <= 14);
+
+			while (*ptr && !isdigit(*ptr))
+				ptr++;
+		}
+
+		if (valid)
+			result += id;
+	}
+
+	return result;
+}
+
+int puzzle2(FILE* fp)
+{	int result = 0;
+
+	char buffer[256];
+	while (fgets(buffer, sizeof(buffer), fp))
+	{
+		const char* ptr = buffer;
+
+		if (strncmp("Game ", ptr, 5))
+			continue;
+		ptr += 5;
+	
+		int id = parse_int_and_advance(ptr);
+		ptr += 2;
+
+		int needed_red = 0;
+		int needed_green = 0;
+		int needed_blue = 0;
+
+		while (*ptr)
+		{
+			int count = parse_int_and_advance(ptr);
+
+			ptr++;
+			if (strncmp(ptr, "red", 3) == 0)
+				needed_red = MAX(needed_red, count);
+			if (strncmp(ptr, "green", 5) == 0)
+				needed_green = MAX(needed_green, count);
+			if (strncmp(ptr, "blue", 4) == 0)
+				needed_blue = MAX(needed_blue, count);
+
+			while (*ptr && !isdigit(*ptr))
+				ptr++;
+		}
+
+		result += needed_red * needed_green * needed_blue;
+	}
+
+	return result;
+}
+
+int main(int argc, char** argv)
+{
+	const char* file_path = "/usr/share/aoc2023/day2_input.txt";
+	if (argc >= 2)
+		file_path = argv[1];
+
+	FILE* fp = fopen(file_path, "r");
+	if (fp == nullptr)
+	{
+		perror("fopen");
+		return 1;
+	}
+
+	printf("puzzle1: %d\n", puzzle1(fp));
+
+	fseek(fp, 0, SEEK_SET);
+
+	printf("puzzle2: %d\n", puzzle2(fp));
+
+	fclose(fp);
+}