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/day06.cpp | 82 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)
 create mode 100644 2017/src/day06.cpp

(limited to '2017/src/day06.cpp')

diff --git a/2017/src/day06.cpp b/2017/src/day06.cpp
new file mode 100644
index 0000000..596ca2c
--- /dev/null
+++ b/2017/src/day06.cpp
@@ -0,0 +1,82 @@
+#include <filesystem>
+#include <fstream>
+#include <iostream>
+#include <map>
+#include <set>
+#include <vector>
+
+using namespace std;
+
+namespace {
+
+vector<int>
+read_lines(const filesystem::path& filename)
+{
+	ifstream    file{ filename };
+	vector<int> lines;
+
+	for ( int value{}; file >> value; ) {
+		lines.emplace_back(value);
+	}
+
+	return lines;
+}
+
+void
+distribute(vector<int>& values)
+{
+	auto iter      = ranges::max_element(values);
+	auto max_value = *iter;
+
+	*iter = 0;
+
+	while ( max_value-- > 0 ) {
+		++iter;
+		if ( iter == values.end() ) {
+			iter = values.begin();
+		}
+		*iter += 1;
+	}
+}
+
+void
+part1(vector<int> values)
+{
+	set<vector<int>> seen;
+	for ( int step = 0;; ++step ) {
+		if ( seen.contains(values) ) {
+			cout << "Part1: " << step << '\n';
+			return;
+		}
+
+		seen.insert(values);
+
+		distribute(values);
+	}
+}
+
+void
+part2(vector<int> values)
+{
+	map<vector<int>, int> seen;
+	for ( int step = 0;; ++step ) {
+		if ( seen.contains(values) ) {
+			cout << "Part2: " << step - seen.at(values) << '\n';
+			return;
+		}
+
+		seen.emplace(values, step);
+
+		distribute(values);
+	}
+}
+
+} // namespace
+
+int
+main()
+{
+	auto values = read_lines("data/day06.txt");
+	part1(values);
+	part2(values);
+}
-- 
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