From 9098c9d0d9922f54b3ad9414151604402b8e9c44 Mon Sep 17 00:00:00 2001
From: Thomas Schmucker <ts@its1.de>
Date: Thu, 2 Jan 2025 14:08:05 +0100
Subject: aoc 2024, day 24, part 2 and day 25

---
 2024/src/day24-alt.cpp | 197 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 197 insertions(+)
 create mode 100644 2024/src/day24-alt.cpp

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

diff --git a/2024/src/day24-alt.cpp b/2024/src/day24-alt.cpp
new file mode 100644
index 0000000..df6d333
--- /dev/null
+++ b/2024/src/day24-alt.cpp
@@ -0,0 +1,197 @@
+#include <array>
+#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;
+}
+
+template<typename Container>
+string
+join(const Container& container, const string& delimiter)
+{
+	ostringstream oss;
+	auto          it = container.begin();
+	if ( it != container.end() ) {
+		oss << *it;
+		++it;
+	}
+	while ( it != container.end() ) {
+		oss << delimiter << *it;
+		++it;
+	}
+	return oss.str();
+}
+
+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;
+}
+
+void
+debug(const tuple<map<string, unsigned long>, map<string, tuple<string, string, string>>>& data)
+{
+	const auto& deps = get<1>(data);
+
+	function<void(const string&, size_t)> eval = [&](const string& input, size_t depth) {
+		if ( !deps.contains(input) ) {
+			return;
+		}
+
+		if ( depth == 3 ) {
+			return;
+		}
+
+		const auto& [lhs, op, rhs] = deps.at(input);
+
+		const string indent(depth * 2, ' ');
+
+		cout << indent << op << " (" << input << ")\n"
+		     << indent << "  - " << lhs << "\n"
+		     << indent << "  - " << rhs << endl;
+
+		eval(lhs, depth + 1);
+		eval(rhs, depth + 1);
+	};
+
+	eval("z02", 0);
+	eval("z16", 0);
+	eval("z17", 0);
+}
+
+void
+part2(const tuple<map<string, unsigned long>, map<string, tuple<string, string, string>>>& data)
+{
+	auto deps = get<1>(data);
+
+	set<string> wrong;
+	for ( const auto& [res, formula]: deps ) {
+		const auto& [op1, op, op2] = formula;
+
+		if ( res.starts_with('z') && op != "XOR" && res != "z45" ) {
+			wrong.insert(res);
+		}
+
+		static const set<char> starts{ 'x', 'y', 'z' };
+
+		if ( op == "XOR" && !starts.contains(res[0]) && !starts.contains(op1[0]) && !starts.contains(op2[0]) ) {
+			wrong.insert(res);
+		}
+
+		if ( op == "AND" && op1 != "x00" && op2 != "x00" ) {
+			for ( const auto& [subres, subformula]: deps ) {
+				const auto& [subop1, subop, subop2] = subformula;
+				if ( (res == subop1 || res == subop2) and subop != "OR" ) {
+					wrong.insert(res);
+				}
+			}
+		}
+
+		if ( op == "XOR" ) {
+			for ( const auto& [subres, subformula]: deps ) {
+				const auto& [subop1, subop, subop2] = subformula;
+				if ( (res == subop1 || res == subop2) and subop == "OR" ) {
+					wrong.insert(res);
+				}
+			}
+		}
+	}
+
+	cout << join(wrong, ",") << endl;
+}
+
+int
+main()
+{
+	const auto data = read_file("data/day24.txt");
+	// debug(data);
+	part1(data);
+	part2(data);
+}
-- 
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