From 870b007c75a3d3c37e89aa4074c2574ac6b5dd81 Mon Sep 17 00:00:00 2001
From: Thomas Schmucker <ts@its1.de>
Date: Tue, 24 Dec 2024 13:00:35 +0100
Subject: aoc 2024, day 24, part 1

---
 2024/src/day24.cpp | 105 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 105 insertions(+)
 create mode 100644 2024/src/day24.cpp

(limited to '2024/src/day24.cpp')

diff --git a/2024/src/day24.cpp b/2024/src/day24.cpp
new file mode 100644
index 0000000..bf439c7
--- /dev/null
+++ b/2024/src/day24.cpp
@@ -0,0 +1,105 @@
+#include <fstream>
+#include <iostream>
+#include <map>
+#include <set>
+#include <sstream>
+#include <string>
+#include <vector>
+using namespace std;
+
+vector<string>
+split(string_view line, string_view delimiter)
+{
+	size_t pos_start = 0;
+	size_t pos_end   = 0;
+
+	vector<string> res;
+
+	while ( (pos_end = line.find(delimiter, pos_start)) != std::string::npos ) {
+		auto token = line.substr(pos_start, pos_end - pos_start);
+		pos_start  = pos_end + delimiter.length();
+
+		res.emplace_back(token);
+	}
+
+	res.emplace_back(line.substr(pos_start));
+	return res;
+}
+
+tuple<map<string, unsigned long>, map<string, tuple<string, string, string>>>
+read_file(string_view filename)
+{
+	fstream    input{ filename };
+	const auto parts = split(string{ istreambuf_iterator<char>{ input }, {} }, "\n\n");
+
+	map<string, unsigned long> inputs;
+
+	// register => { reg1 operator reg2 }
+	map<string, tuple<string, string, string>> deps;
+
+	stringstream spart1{ parts[0] };
+	for ( string line; getline(spart1, line); ) {
+		const auto foo = split(line, ": ");
+		inputs[foo[0]] = stoul(foo[1]);
+	}
+
+	stringstream spart2{ parts[1] };
+	for ( string line; getline(spart2, line); ) {
+		const auto foo = split(line, " ");
+		deps[foo[4]]   = { foo[0], foo[1], foo[2] };
+	}
+
+	return { inputs, deps };
+}
+
+void
+part1(const tuple<map<string, unsigned long>, map<string, tuple<string, string, string>>>& data)
+{
+	auto        inputs = get<0>(data);
+	const auto& deps   = get<1>(data);
+
+	function<unsigned long(const string&)> eval = [&](const string& input) -> unsigned long {
+		if ( inputs.contains(input) ) {
+			return inputs.at(input);
+		}
+
+		const auto& [lhs, op, rhs] = deps.at(input);
+
+		unsigned long value = 0;
+
+		if ( op == "XOR" ) {
+			value = eval(lhs) ^ eval(rhs);
+		}
+		else if ( op == "AND" ) {
+			value = eval(lhs) & eval(rhs);
+		}
+		else if ( op == "OR" ) {
+			value = eval(lhs) | eval(rhs);
+		}
+		else {
+			cerr << "Das darf nicht passieren! Input: " << input << endl;
+		}
+
+		inputs[input] = value;
+
+		return value;
+	};
+
+	unsigned long value = 0;
+	for ( const auto& [first, second]: deps ) {
+		if ( first.starts_with("z") ) {
+			if ( eval(first) != 0 ) {
+				auto bit = stoul(first.substr(1));
+				value |= 1UL << bit;
+			}
+		}
+	}
+	cout << value << endl;
+}
+
+int
+main()
+{
+	const auto data = read_file("data/day24.txt");
+	part1(data);
+}
-- 
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