From 528c58bf205864e2797e2027fa9691c5f0ba1249 Mon Sep 17 00:00:00 2001
From: Thomas Schmucker <ts@its1.de>
Date: Sun, 12 Jan 2025 10:29:51 +0100
Subject: aoc 2016, day 2

---
 2016/src/day02.cpp | 114 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 114 insertions(+)
 create mode 100644 2016/src/day02.cpp

(limited to '2016/src/day02.cpp')

diff --git a/2016/src/day02.cpp b/2016/src/day02.cpp
new file mode 100644
index 0000000..ad625d5
--- /dev/null
+++ b/2016/src/day02.cpp
@@ -0,0 +1,114 @@
+#include <fstream>
+#include <iostream>
+#include <map>
+#include <string>
+#include <tuple>
+#include <vector>
+
+using namespace std;
+
+vector<string>
+read_file(string_view filename)
+{
+	fstream        input{ filename };
+	vector<string> lines;
+
+	vector<tuple<char, long>> result;
+	for ( string line; getline(input, line); ) {
+		lines.emplace_back(line);
+	}
+	return lines;
+}
+
+void
+part1(const vector<string>& lines)
+{
+	int pos_x = 1;
+	int pos_y = 1;
+
+	for ( const auto& line: lines ) {
+		for ( const auto chr: line ) {
+			switch ( chr ) {
+			case 'U':
+				--pos_y;
+				break;
+			case 'R':
+				++pos_x;
+				break;
+			case 'L':
+				--pos_x;
+				break;
+			case 'D':
+				++pos_y;
+				break;
+			default:
+				cerr << "unknown char: " << chr << endl;
+				return;
+			}
+
+			pos_x = clamp(pos_x, 0, 2);
+			pos_y = clamp(pos_y, 0, 2);
+		}
+		cout << pos_y * 3 + pos_x + 1;
+	}
+	cout << endl;
+}
+
+void
+part2(const vector<string>& lines)
+{
+	const map<tuple<int, int>, char> keypad = {
+		{ { 2, 0 }, '1' },
+		{ { 1, 1 }, '2' },
+		{ { 2, 1 }, '3' },
+		{ { 3, 1 }, '4' },
+		{ { 0, 2 }, '5' },
+		{ { 1, 2 }, '6' },
+		{ { 2, 2 }, '7' },
+		{ { 3, 2 }, '8' },
+		{ { 4, 2 }, '9' },
+		{ { 1, 3 }, 'A' },
+		{ { 2, 3 }, 'B' },
+		{ { 3, 3 }, 'C' },
+		{ { 2, 4 }, 'D' }
+	};
+
+	tuple<int, int> pos = { 0, 2 };
+
+	for ( const auto& line: lines ) {
+		for ( const auto chr: line ) {
+			auto pos2 = pos;
+			switch ( chr ) {
+			case 'U':
+				--get<1>(pos2);
+				break;
+			case 'R':
+				++get<0>(pos2);
+				break;
+			case 'L':
+				--get<0>(pos2);
+				break;
+			case 'D':
+				++get<1>(pos2);
+				break;
+			default:
+				cerr << "unknown char: " << chr << endl;
+				return;
+			}
+
+			if ( keypad.contains(pos2) ) {
+				pos = pos2;
+			}
+		}
+		cout << keypad.at(pos);
+	}
+	cout << endl;
+}
+
+int
+main()
+{
+	auto lines = read_file("data/day02.txt");
+	part1(lines);
+	part2(lines);
+}
-- 
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