From 7634cf6ee1a1681586cc550942eaff87076add02 Mon Sep 17 00:00:00 2001
From: Thomas Schmucker <ts@its1.de>
Date: Sat, 6 Dec 2025 10:48:04 +0100
Subject: aoc 2025, day 6

---
 2025/src/day06.cpp | 151 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 151 insertions(+)
 create mode 100644 2025/src/day06.cpp

(limited to '2025/src')

diff --git a/2025/src/day06.cpp b/2025/src/day06.cpp
new file mode 100644
index 0000000..af562cd
--- /dev/null
+++ b/2025/src/day06.cpp
@@ -0,0 +1,151 @@
+#include <filesystem>
+#include <fstream>
+#include <iostream>
+#include <sstream>
+#include <string>
+#include <tuple>
+#include <vector>
+
+using namespace std;
+
+namespace {
+
+using Grid = vector<vector<long>>;
+using Ops  = vector<char>;
+
+vector<string>
+read_file(const filesystem::path& filename)
+{
+	ifstream       file{ filename };
+	vector<string> lines;
+
+	for ( string line; getline(file, line); ) {
+		lines.emplace_back(line);
+	}
+
+	return lines;
+}
+
+vector<char>
+read_ops(const string& line)
+{
+	stringstream strm{ line };
+	vector<char> ops;
+	for ( char chr{}; strm >> chr; ) {
+		ops.emplace_back(chr);
+	}
+	return ops;
+}
+
+vector<long>
+read_numbers(const string& line)
+{
+	stringstream strm{ line };
+	vector<long> numbers;
+	for ( long number{}; strm >> number; ) {
+		numbers.emplace_back(number);
+	}
+	return numbers;
+}
+
+void
+part1(vector<string> lines)
+{
+	ranges::reverse(lines);
+
+	const auto ops = read_ops(lines[0]);
+
+	vector<vector<long>> grid;
+	for ( size_t i = 1; i < lines.size(); ++i ) {
+		grid.emplace_back(read_numbers(lines[i]));
+	}
+
+	long sum = 0;
+	for ( size_t col = 0; col != ops.size(); ++col ) {
+		long value = ops[col] == '*' ? 1 : 0;
+		for ( auto& row: grid ) {
+			if ( ops[col] == '*' ) {
+				value *= row[col];
+			}
+			else {
+				value += row[col];
+			}
+		}
+		sum += value;
+	}
+	cout << "Part 1: " << sum << '\n';
+}
+
+vector<string>
+rotateLeft90(const vector<string>& matrix)
+{
+	if ( matrix.empty() ) {
+		return {};
+	}
+
+	auto rows = matrix.size();
+	auto cols = matrix[0].size();
+
+	vector<string> res(cols, string(rows, ' '));
+
+	for ( size_t row = 0; row != rows; ++row ) {
+		for ( size_t col = 0; col != cols; ++col ) {
+			// Position aus ursprünglicher Matrix auf neue übertragen
+			res[cols - 1 - col][row] = matrix[row][col];
+		}
+	}
+
+	return res;
+}
+
+void
+part2(vector<string> lines)
+{
+	auto ops = read_ops(lines.back());
+	ranges::reverse(ops);
+	lines.pop_back(); // ops entfernen
+
+	// Matrix drehen
+	lines = rotateLeft90(lines);
+	lines.emplace_back("");
+
+	vector<vector<long>> grid;
+	vector<long>         curr;
+
+	// Matrix neu aufbauen
+	for ( const auto& line: lines ) {
+		if ( long number{}; sscanf(line.data(), "%ld", &number) == 1 ) {
+			curr.emplace_back(number);
+		}
+		else {
+			grid.emplace_back(curr);
+			curr.clear();
+		}
+	}
+
+	// ausrechnen
+	long sum = 0;
+	for ( size_t row = 0; row != ops.size(); ++row ) {
+		long value = ops[row] == '*' ? 1 : 0;
+		for ( const auto number: grid[row] ) {
+			if ( ops[row] == '*' ) {
+				value *= number;
+			}
+			else {
+				value += number;
+			}
+		}
+		sum += value;
+	}
+	cout << "Part 2: " << sum << '\n';
+}
+
+} // namespace
+
+int
+main()
+{
+	const auto lines = read_file("data/day06.txt");
+	part1(lines);
+	part2(lines);
+}
-- 
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