Add solution for "Day 21: Keypad Conundrum", part 2

include/aoc/extra/KeypadPatternTransformation.hpp

@@ -0,0 +1,28 @@
+// Solutions to the Advent Of Code 2024.
+// Copyright (C) 2025  Stefan Müller
+//
+// This program is free software: you can redistribute it and/or modify it under
+// the terms of the GNU General Public License as published by the Free Software
+// Foundation, either version 3 of the License, or (at your option) any later
+// version.
+//
+// This program is distributed in the hope that it will be useful, but WITHOUT
+// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+// FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along with
+// this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#pragma once
+
+#include <string>
+#include <vector>
+
+class KeypadPatternTransformation
+{
+public:
+    int nDuplicates{ 0 };
+    std::vector<std::string> parts{};
+    std::vector<KeypadPatternTransformation*> partPtrs{};
+    std::vector<int64_t> accumulatedLengths{};
+};

include/aoc/extra/KeypadRobot.hpp

@@ -18,15 +18,18 @@
 #include <map>
 #include <string>
 
+#include <aoc/extra/KeypadPatternTransformation.hpp>
 #include <aoc/common/Point2.hpp>
 
 class KeypadRobot
 {
 public:
     KeypadRobot(const std::map<char, Point2>&& keypad, const Point2&& forbidden);
-    std::string calcInputKeys(const std::string& targetOutputKeys) const;
+    KeypadPatternTransformation calcTransformation(const std::string& targetOutputKeys) const;
 private:
     const std::map<char, Point2> keypad_;
     const Point2 forbidden_;
-    void move(std::ostringstream& stream, const int delta, const char positive, const char negative) const;
+    void move(std::ostringstream& stream, const int delta, const char positive, const char negative,
+        int& nDuplicates) const;
+    bool isForbidden(const int x, const int y) const;
 };