From c643fd165a82fa661552f5734397bda620ec7255 Mon Sep 17 00:00:00 2001
From: Connor De Meyer <connordemeyer@gmail.com>
Date: Fri, 29 Aug 2025 17:44:39 +0900
Subject: [PATCH] function selector bug fix

---
 demos/sudoku/sudoku.h  |  1 +
 include/nd-wfc/wfc.hpp | 35 ++++++++++++++++++-----------------
 2 files changed, 19 insertions(+), 17 deletions(-)

diff --git a/demos/sudoku/sudoku.h b/demos/sudoku/sudoku.h
index 3e71bff..d22b0f7 100644
--- a/demos/sudoku/sudoku.h
+++ b/demos/sudoku/sudoku.h
@@ -264,5 +264,6 @@ using SudokuSolver = WFC::Builder<Sudoku>
                     }
                 }
             }
+            
         }), 1, 2, 3, 4, 5, 6, 7, 8, 9>
         ::Build;
\ No newline at end of file
diff --git a/include/nd-wfc/wfc.hpp b/include/nd-wfc/wfc.hpp
index 2f9fc91..f5fab33 100644
--- a/include/nd-wfc/wfc.hpp
+++ b/include/nd-wfc/wfc.hpp
@@ -149,14 +149,14 @@ template<std::size_t I,
     typename NewConstrainerFunctionT, 
     typename SelectedIDsVariableIDMapT,
     typename EmptyFunctionT>
-using MergedConstrainerElementSelector = std::conditional_t<
-    (I < ConstrainerFunctionMapT::size()), // if the index is within the size of the tuple
-        std::conditional_t<SelectedIDsVariableIDMapT::template HasValue<VariableIDMapT::GetValueConsteval(I)>(), // if the value is in the selected IDs
-            NewConstrainerFunctionT,
-            std::tuple_element_t<std::min(I, ConstrainerFunctionMapT::size() - 1), typename ConstrainerFunctionMapT::TupleType>
-        >,
-    EmptyFunctionT
->;
+using MergedConstrainerElementSelector = 
+    std::conditional_t<SelectedIDsVariableIDMapT::template HasValue<VariableIDMapT::GetValueConsteval(I)>(), // if the value is in the selected IDs
+        NewConstrainerFunctionT,
+        std::conditional_t<(I < ConstrainerFunctionMapT::size()), // if the index is within the size of the tuple
+                std::tuple_element_t<std::min(I, ConstrainerFunctionMapT::size() - 1), typename ConstrainerFunctionMapT::TupleType>,
+                EmptyFunctionT
+            >
+    >;
 
 // Helper to make a merged constrainer function map
 template<typename VariableIDMapT, 
@@ -368,11 +368,13 @@ public:
             if (!Propagate(state))
                 return false;
 
-            if (state.wave.IsFullyCollapsed()) {
+            if (state.wave.HasContradiction())
+                return false;
+
+            if (state.wave.IsFullyCollapsed())
                 return true;
-            } else {
-                Branch(state);
-            }
+
+            Branch(state);
         }
         return false;
     }
@@ -426,7 +428,7 @@ private:
         assert(!state.wave.IsCollapsed(minEntropyCell));
 
         // create a list of possible values
-        size_t availableValues = state.wave.Entropy(minEntropyCell);
+        uint16_t availableValues = state.wave.Entropy(minEntropyCell);
         std::array<uint16_t, VariableIDMapT::ValuesRegisteredAmount> possibleValues; // inplace vector
         MaskType mask = state.wave.GetMask(minEntropyCell);
         for (size_t i = 0; i < availableValues; ++i) 
@@ -441,10 +443,10 @@ private:
         }
 
         // randomly select a value from possible values
-        for (size_t i = 0; i < availableValues; ++i) 
+        for (size_t i = 0; i < availableValues; ++i)
         {
-            std::uniform_int_distribution<uint16_t> dist(0, availableValues - 1);
-            uint16_t selectedValue = possibleValues[dist(state.rng)];
+            std::uniform_int_distribution<size_t> dist(0, availableValues - 1);
+            size_t selectedValue = possibleValues[dist(state.rng)];
             
             {
                 // copy the state and branch out
@@ -503,7 +505,6 @@ private:
         }
     }
 
-private:
     static void PropogateInitialValues(SolverState& state)
     {
         auto allValues = VariableIDMapT::GetAllValues();