1 files changed, 97 insertions, 0 deletions

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);
+}