2 files changed, 21 insertions, 1 deletions
diff --git a/puzzle.cpp b/puzzle.cpp
index 0e3574b..50b32af 100644
--- a/puzzle.cpp
+++ b/puzzle.cpp
@@ -35,7 +35,7 @@ static void find_path_to_picture(std::string& path, int number)
         std::to_string(number % puzzles_per_side) + ".jpg";
 }
 
-void GameParams::CreateNewPuzzles()
+void GameParams::NextUntestedPuzzles()
 {
     int idx_random_puzzle;
     std::unique_ptr<Puzzle> tmp_puzzle;
@@ -65,6 +65,24 @@ void GameParams::CreateNewPuzzles()
         tmp_puzzle->callback(press_button_callback, this);
         puzzles.push_back(std::move(tmp_puzzle));
     }
+    ResetFreePuzzles();
+}
+
+bool GameParams::IsSolvability()
+{
+    int counter = 0;
+    for(size_t i = 0; i < puzzles.size(); ++i)
+        for(size_t j = i+1; j < puzzles.size(); ++j)
+            if(puzzles[i]->sequence_number > puzzles[j]->sequence_number)
+                ++counter;
+    return counter % 2 == 0;
+}
+
+void GameParams::CreateNewPuzzles()
+{
+    do {
+        NextUntestedPuzzles();
+    } while(!IsSolvability());
 }
 
 void GameParams::NewGame()
diff --git a/puzzle.hpp b/puzzle.hpp
index 5b2b2ab..5f51877 100644
--- a/puzzle.hpp
+++ b/puzzle.hpp
@@ -36,6 +36,8 @@ private:
     GameParams() {}
     void CalculateStandardPuzzlePos();
     void ResetFreePuzzles();
+    void NextUntestedPuzzles();
+    bool IsSolvability();
     void CreateNewPuzzles();
 public:
     void NewGame();