From 92e510305a8cb6c92bc39e601424c60c698e4adf Mon Sep 17 00:00:00 2001
From: Thomas Schmucker <ts@its1.de>
Date: Sun, 28 Apr 2024 13:33:11 +0200
Subject: day 5, advent of code 2022

---
 2022/src/day05.cpp | 97 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 97 insertions(+)
 create mode 100644 2022/src/day05.cpp

(limited to '2022/src/day05.cpp')

diff --git a/2022/src/day05.cpp b/2022/src/day05.cpp
new file mode 100644
index 0000000..e9e2097
--- /dev/null
+++ b/2022/src/day05.cpp
@@ -0,0 +1,97 @@
+#include <fstream>
+#include <iostream>
+#include <map>
+#include <stack>
+#include <string>
+#include <tuple>
+#include <vector>
+using namespace std;
+
+using instructions_t = vector<tuple<size_t, size_t, size_t>>;
+using stacks_t       = map<size_t, stack<char>>;
+
+void
+read_file(string_view filename, instructions_t& instructions, stacks_t& stacks)
+{
+	fstream        input{ filename };
+	vector<string> lines;
+
+	instructions.clear();
+
+	for ( string line; getline(input, line); ) {
+		if ( line.length() == 0 ) {
+			continue;
+		}
+		else if ( line.starts_with("move") ) {
+			size_t a, b, c;
+			sscanf(line.c_str(), "move %zu from %zu to %zu", &a, &b, &c);
+			instructions.emplace_back(a, b, c);
+		}
+		else if ( line.find('[') != string::npos ) {
+			lines.emplace_back(line);
+		}
+	}
+
+	reverse(begin(lines), end(lines));
+	stacks.clear();
+
+	for ( const auto& line: lines ) {
+		for ( size_t col = 0; col * 4 < line.length(); ++col ) {
+			auto chr = line[col * 4 + 1];
+			if ( isalpha(chr) != 0 ) {
+				stacks[col + 1].push(chr);
+			}
+		}
+	}
+}
+
+void
+part1(const instructions_t& instructions, stacks_t stacks)
+{
+	for ( const auto& [amount, from, to]: instructions ) {
+		for ( size_t i = 0; i != amount; ++i ) {
+			const auto value = stacks[from].top();
+			stacks[from].pop();
+			stacks[to].emplace(value);
+		}
+	}
+	for ( size_t i = 0; i != stacks.size(); ++i ) {
+		cout << stacks[i + 1].top();
+	}
+	cout << endl;
+}
+
+void
+part2(const instructions_t& instructions, stacks_t stacks)
+{
+	for ( const auto& [amount, from, to]: instructions ) {
+		vector<char> values;
+
+		for ( size_t i = 0; i != amount; ++i ) {
+			const auto value = stacks[from].top();
+			stacks[from].pop();
+			values.emplace_back(value);
+		}
+
+		reverse(begin(values), end(values));
+
+		for ( const auto& value: values ) {
+			stacks[to].emplace(value);
+		}
+	}
+	for ( size_t i = 0; i != stacks.size(); ++i ) {
+		cout << stacks[i + 1].top();
+	}
+	cout << endl;
+}
+
+int
+main()
+{
+	instructions_t instructions;
+	stacks_t       stacks;
+
+	read_file("data/day05.txt", instructions, stacks);
+	part1(instructions, stacks);
+	part2(instructions, stacks);
+}
-- 
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