From 765223e3a1bd4d3be8cb2c8b11e2b836e5690038 Mon Sep 17 00:00:00 2001
From: Thomas Schmucker <ts@its1.de>
Date: Wed, 3 Dec 2025 17:02:20 +0100
Subject: aoc 2025, day 3, part 1

---
 2025/src/day03.cpp | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)
 create mode 100644 2025/src/day03.cpp

(limited to '2025')

diff --git a/2025/src/day03.cpp b/2025/src/day03.cpp
new file mode 100644
index 0000000..c131255
--- /dev/null
+++ b/2025/src/day03.cpp
@@ -0,0 +1,50 @@
+#include <algorithm>
+#include <cctype>
+#include <filesystem>
+#include <fstream>
+#include <iostream>
+#include <vector>
+
+using namespace std;
+
+namespace {
+
+vector<vector<long>>
+read_file(const filesystem::path& filename)
+{
+	ifstream             file{ filename };
+	vector<vector<long>> lines;
+
+	for ( string line; getline(file, line); ) {
+		vector<long> numbers;
+		for ( auto chr: line ) {
+			if ( isdigit(chr) ) {
+				numbers.emplace_back(chr - '0');
+			}
+		}
+		lines.emplace_back(std::move(numbers));
+	}
+
+	return lines;
+}
+
+void
+part1(const vector<vector<long>>& lines)
+{
+	long sum = 0;
+	for ( const auto& line: lines ) {
+		auto first  = max_element(line.begin(), prev(line.end()));
+		auto second = max_element(next(first), line.end());
+		sum += *first * 10 + *second;
+	}
+	cout << "Part 1: " << sum << '\n';
+}
+
+} // namespace
+
+int
+main()
+{
+	auto lines = read_file("data/day03.txt");
+	part1(lines);
+}
-- 
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