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/day01.cpp | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)
 create mode 100644 2018/src/day01.cpp

(limited to '2018/src/day01.cpp')

diff --git a/2018/src/day01.cpp b/2018/src/day01.cpp
new file mode 100644
index 0000000..d57a187
--- /dev/null
+++ b/2018/src/day01.cpp
@@ -0,0 +1,58 @@
+#include <filesystem>
+#include <fstream>
+#include <iostream>
+#include <numeric>
+#include <unordered_set>
+#include <vector>
+
+using namespace std;
+
+namespace {
+
+vector<long>
+read_file(const filesystem::path& filename)
+{
+	ifstream     file{ filename };
+	vector<long> values;
+
+	for ( long value = 0; file >> value; ) {
+		values.emplace_back(value);
+	}
+
+	return values;
+}
+
+void
+part1(const vector<long>& values)
+{
+	auto sum = accumulate(values.begin(), values.end(), 0L);
+	cout << "Part1: " << sum << '\n';
+}
+
+void
+part2(const vector<long>& values)
+{
+	unordered_set<long> seen;
+
+	long sum = 0;
+	for ( size_t idx = 0;; ++idx ) {
+		sum += values.at(idx % values.size());
+
+		if ( seen.contains(sum) ) {
+			cout << "Part2: " << sum << '\n';
+			return;
+		}
+
+		seen.emplace(sum);
+	}
+}
+
+} // namespace
+
+int
+main()
+{
+	auto values = read_file("data/day01.txt");
+	part1(values);
+	part2(values);
+}
-- 
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