From 756f22d58bb198b8f34589c112e1003614ccdcd6 Mon Sep 17 00:00:00 2001
From: Thomas Schmucker <ts@its1.de>
Date: Sun, 2 Nov 2025 21:41:58 +0100
Subject: aoc 2017, days 1-20

---
 2017/src/day17.cpp | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)
 create mode 100644 2017/src/day17.cpp

(limited to '2017/src/day17.cpp')

diff --git a/2017/src/day17.cpp b/2017/src/day17.cpp
new file mode 100644
index 0000000..6cf498b
--- /dev/null
+++ b/2017/src/day17.cpp
@@ -0,0 +1,47 @@
+#include <iostream>
+#include <vector>
+
+using namespace std;
+
+namespace {
+
+void
+part1(size_t steps, size_t iterations)
+{
+	vector<size_t> buffer{ 0 };
+	size_t         pos = 0;
+
+	for ( size_t i = 1; i <= iterations; ++i ) {
+		pos = (pos + steps) % i + 1;
+		buffer.insert(buffer.begin() + static_cast<vector<size_t>::difference_type>(pos), i);
+	}
+
+	cout << "Part1: " << buffer[(pos + 1) % buffer.size()] << '\n';
+}
+
+void
+part2(size_t steps, size_t iterations)
+{
+	size_t pos   = 0;
+	size_t value = 0;
+
+	for ( size_t i = 1; i <= iterations; ++i ) {
+		pos = (pos + steps) % i;
+		if ( pos == 0 ) {
+			value = i;
+		}
+		pos = (pos + 1) % (i + 1);
+	}
+
+	cout << "Part2: " << value << '\n';
+}
+
+} // namespace
+
+int
+main()
+{
+	const auto input = 371;
+	part1(input, 2017);
+	part2(input, 50'000'000);
+}
-- 
cgit v1.3