From 8c96639ec1f6757570510fc27f1c5fabece35eaf Mon Sep 17 00:00:00 2001
From: Thomas Schmucker <ts@its1.de>
Date: Sun, 16 Nov 2025 13:23:34 +0100
Subject: aoc 2018, days 1-11

---
 2018/src/day08.cpp | 88 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 88 insertions(+)
 create mode 100644 2018/src/day08.cpp

(limited to '2018/src/day08.cpp')

diff --git a/2018/src/day08.cpp b/2018/src/day08.cpp
new file mode 100644
index 0000000..9c2a093
--- /dev/null
+++ b/2018/src/day08.cpp
@@ -0,0 +1,88 @@
+#include <filesystem>
+#include <fstream>
+#include <iostream>
+#include <vector>
+
+using namespace std;
+
+namespace {
+
+vector<int>
+read_file(const filesystem::path& filename)
+{
+	ifstream    file{ filename };
+	vector<int> data;
+
+	for ( int number{}; file >> number; ) {
+		data.emplace_back(number);
+	}
+
+	return data;
+}
+
+void
+part1(const vector<int>& data)
+{
+	size_t idx = 0;
+	int    sum = 0;
+
+	function<void()> func = [&] {
+		auto count_child = data.at(idx++);
+		auto count_meta  = data.at(idx++);
+
+		while ( count_child-- > 0 ) {
+			func();
+		}
+
+		while ( count_meta-- > 0 ) {
+			sum += data.at(idx++);
+		}
+	};
+
+	func();
+
+	cout << "Part 1: " << sum << '\n';
+}
+
+void
+part2(const vector<int>& data)
+{
+	size_t idx = 0;
+
+	function<int()> func = [&] {
+		const auto count_child = data.at(idx++);
+		const auto count_meta  = data.at(idx++);
+
+		vector<int> child_values;
+		for ( int i = 0; i != count_child; ++i ) {
+			child_values.emplace_back(func());
+		}
+
+		int value = 0;
+		for ( int i = 0; i != count_meta; ++i ) {
+			auto meta = data.at(idx++);
+			if ( count_child == 0 ) {
+				value += meta;
+			}
+			else {
+				meta--;
+				if ( meta >= 0 && meta < count_child ) {
+					value += child_values[static_cast<size_t>(meta)];
+				}
+			}
+		}
+		return value;
+	};
+
+	cout << "Part 2: " << func() << '\n';
+}
+
+} // namespace
+
+int
+main()
+{
+	auto data = read_file("data/day08.txt");
+	part1(data);
+	part2(data);
+}
-- 
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