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/day01.cpp | 44 +++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 43 insertions(+), 1 deletion(-)

(limited to '2017/src/day01.cpp')

diff --git a/2017/src/day01.cpp b/2017/src/day01.cpp
index 4a3fd99..f8297e7 100644
--- a/2017/src/day01.cpp
+++ b/2017/src/day01.cpp
@@ -1,9 +1,51 @@
+#include <filesystem>
+#include <fstream>
 #include <iostream>
+#include <string>
 
 using namespace std;
 
+namespace {
+
+string
+read_line(const filesystem::path& filename)
+{
+	ifstream file{ filename };
+	string   line;
+	getline(file, line);
+	return line;
+}
+
+long
+calculate(string_view captcha, size_t offset)
+{
+	long sum = 0;
+	for ( size_t i = 0; i != captcha.size(); ++i ) {
+		if ( captcha[i] == captcha[(i + offset) % captcha.size()] ) {
+			sum += captcha[i] - '0';
+		}
+	}
+	return sum;
+}
+
+void
+part1(string_view captcha)
+{
+	cout << "Part1: " << calculate(captcha, 1) << '\n';
+}
+
+void
+part2(string_view captcha)
+{
+	cout << "Part2: " << calculate(captcha, captcha.size() / 2) << '\n';
+}
+
+} // namespace
+
 int
 main()
 {
-	cout << "Hallo Welt" << '\n';
+	auto captcha = read_line("data/day01.txt");
+	part1(captcha);
+	part2(captcha);
 }
-- 
cgit v1.3