aoc2025: Implement day1 solution

userspace/aoc2025/CMakeLists.txt

@@ -1,4 +1,5 @@
 set(AOC2025_PROJECTS
+	day1
 	full
 )
 

userspace/aoc2025/day1/CMakeLists.txt

@@ -0,0 +1,9 @@
+set(SOURCES
+	main.cpp
+)
+
+add_executable(aoc2025_day1 ${SOURCES})
+banan_include_headers(aoc2025_day1 ban)
+banan_link_library(aoc2025_day1 libc)
+
+install(TARGETS aoc2025_day1 OPTIONAL)

userspace/aoc2025/day1/main.cpp

@@ -0,0 +1,87 @@
+#include <inttypes.h>
+#include <stdio.h>
+
+using i8  = int8_t;
+using i16 = int16_t;
+using i32 = int32_t;
+using i64 = int64_t;
+
+using u8  = uint8_t;
+using u16 = uint16_t;
+using u32 = uint32_t;
+using u64 = uint64_t;
+
+i64 part1(FILE* fp)
+{
+	int amount;
+	char direction;
+
+	i32 value = 50;
+	i32 result = 0;
+	while (fscanf(fp, "%c%d\n", &direction, &amount) == 2)
+	{
+		switch (direction)
+		{
+			case 'L':
+				value = (value - amount) % 100;
+				break;
+			case 'R':
+				value = (value + amount) % 100;
+				break;
+		}
+
+		if (value == 0)
+			result++;
+	}
+
+	return result;
+}
+
+i64 part2(FILE* fp)
+{
+	int amount;
+	char direction;
+
+	i32 value = 50;
+	i32 result = 0;
+	while (fscanf(fp, "%c%d\n", &direction, &amount) == 2)
+	{
+		switch (direction)
+		{
+			case 'L':
+				if (amount >= value)
+					result += (value != 0) + (amount - value) / 100;
+				value = (((value - amount) % 100) + 100) % 100;
+				break;
+			case 'R':
+				result += (value + amount) / 100;
+				value = (value + amount) % 100;
+				break;
+		}
+	}
+
+	return result;
+}
+
+int main(int argc, char** argv)
+{
+	const char* file_path = "/usr/share/aoc2025/day1_input.txt";
+
+	if (argc >= 2)
+		file_path = argv[1];
+
+	FILE* fp = fopen(file_path, "r");
+	if (fp == nullptr)
+	{
+		perror("fopen");
+		return 1;
+	}
+
+	printf("part1: %" PRId64 "\n", part1(fp));
+
+	fseek(fp, 0, SEEK_SET);
+
+	printf("part2: %" PRId64 "\n", part2(fp));
+
+	fclose(fp);
+}