From edeb667eadd563d229855a77837fa57ec7edf60f Mon Sep 17 00:00:00 2001
From: Bananymous <oskari.alaranta@bananymous.com>
Date: Fri, 12 Dec 2025 06:30:03 +0200
Subject: [PATCH] aoc2025: Implement day5 solution

---
 userspace/aoc2025/CMakeLists.txt      |   1 +
 userspace/aoc2025/day5/CMakeLists.txt |   9 +++
 userspace/aoc2025/day5/main.cpp       | 106 ++++++++++++++++++++++++++
 3 files changed, 116 insertions(+)
 create mode 100644 userspace/aoc2025/day5/CMakeLists.txt
 create mode 100644 userspace/aoc2025/day5/main.cpp

diff --git a/userspace/aoc2025/CMakeLists.txt b/userspace/aoc2025/CMakeLists.txt
index fc6013e2..6a8146cb 100644
--- a/userspace/aoc2025/CMakeLists.txt
+++ b/userspace/aoc2025/CMakeLists.txt
@@ -3,6 +3,7 @@ set(AOC2025_PROJECTS
 	day2
 	day3
 	day4
+	day5
 	full
 )
 
diff --git a/userspace/aoc2025/day5/CMakeLists.txt b/userspace/aoc2025/day5/CMakeLists.txt
new file mode 100644
index 00000000..236105e5
--- /dev/null
+++ b/userspace/aoc2025/day5/CMakeLists.txt
@@ -0,0 +1,9 @@
+set(SOURCES
+	main.cpp
+)
+
+add_executable(aoc2025_day5 ${SOURCES})
+banan_include_headers(aoc2025_day5 ban)
+banan_link_library(aoc2025_day5 libc)
+
+install(TARGETS aoc2025_day5 OPTIONAL)
diff --git a/userspace/aoc2025/day5/main.cpp b/userspace/aoc2025/day5/main.cpp
new file mode 100644
index 00000000..37e07736
--- /dev/null
+++ b/userspace/aoc2025/day5/main.cpp
@@ -0,0 +1,106 @@
+#include <BAN/Vector.h>
+#include <BAN/Sort.h>
+
+#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;
+
+struct Range
+{
+	u64 min;
+	u64 max;
+};
+
+static BAN::Vector<Range> parse_ranges(FILE* fp)
+{
+	BAN::Vector<Range> ranges;
+
+	u64 min, max;
+	ungetc('\n', fp);
+	while (fscanf(fp, "\n%" SCNu64 "-%" SCNu64, &min, &max) == 2)
+		MUST(ranges.emplace_back(min, max));
+
+	return ranges;
+}
+
+i64 part1(FILE* fp)
+{
+	auto ranges = parse_ranges(fp);
+
+	i64 result = 0;
+
+	u64 value;
+	while (fscanf(fp, "%" SCNu64, &value) == 1)
+	{
+		bool is_fresh = false;
+		for (const auto range : ranges)
+			if (range.min <= value && value <= range.max)
+				is_fresh = true;
+		result += is_fresh;
+	}
+
+	return result;
+}
+
+i64 part2(FILE* fp)
+{
+	auto ranges = parse_ranges(fp);
+
+	BAN::sort::sort(ranges.begin(), ranges.end(),
+		[](auto lhs, auto rhs) -> bool
+		{
+			return lhs.min < rhs.min;
+		}
+	);
+
+	for (size_t i = 0; i < ranges.size() - 1; i++)
+	{
+		auto& lhs = ranges[i];
+		auto& rhs = ranges[i + 1];
+		if (lhs.min > rhs.max || rhs.min > lhs.max)
+			continue;
+
+		lhs.min = BAN::Math::min(lhs.min, rhs.min);
+		lhs.max = BAN::Math::max(lhs.max, rhs.max);
+		ranges.remove(i + 1);
+
+		i--;
+	}
+
+	i64 result = 0;
+	for (auto range : ranges)
+		result += range.max - range.min + 1;
+	return result;
+}
+
+int main(int argc, char** argv)
+{
+	const char* file_path = "/usr/share/aoc2025/day5_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);
+}