feat: dim already compared elements in merge sort

Previously, all elements in the left and right subarrays would be
highlighted. Now, those elements that have already been passed over will
be dimmed.

levels/merge_sort.gd

@@ -24,11 +24,11 @@ func _init(array).(array):
     pass
 
 func next(action):
-    if _left == -1:
+    if _left == _get_middle():
         if action != null and action != ACTIONS.RIGHT:
             return emit_signal("mistake")
         _right += 1
-    elif _right == -1:
+    elif _right == _get_end():
         if action != null and action != ACTIONS.LEFT:
             return emit_signal("mistake")
         _left += 1
@@ -40,30 +40,26 @@ func next(action):
         if action != null and action != ACTIONS.RIGHT:
             return emit_signal("mistake")
         _right += 1
-    # Test if end of subarrays have been reached
-    if _left == _get_middle():
-        _left = -1
-    if _right == _get_end():
-        _right = -1
     # If both ends have been reached, merge and advance to next block
-    if _left == -1 and _right == -1:
+    if _left == _get_middle() and _right == _get_end():
         array.sort(_get_begin(), _get_end())
         _sub_no += 1
-        _left = _get_begin()
-        _right = _get_middle()
         # If last block has been completed, go up a level
         if _sub_no == array.size / (_sub_size):
             _sub_size *= 2
             _sub_no = 0
-            _left = _get_begin()
-            _right = _get_middle()
             if _sub_size == array.size * 2:
                 emit_signal("done")
+        # Update pointers
+        _left = _get_begin()
+        _right = _get_middle()
 
 func get_effect(i):
-    if i == _left or i == _right:
+    var is_left = _left != _get_middle() and i == _left
+    var is_right = _right != _get_end() and i == _right
+    if is_left or is_right:
         return EFFECTS.HIGHLIGHTED
-    if i < _sub_no * _sub_size or i >= _sub_no * _sub_size + _sub_size:
+    if i < _left or i >= _get_middle() and i < _right or i >= _get_end():
         return EFFECTS.DIMMED
     return EFFECTS.NONE
 

project.godot

@@ -45,11 +45,6 @@ _global_script_classes=[ {
 "path": "res://levels/merge_sort.gd"
 }, {
 "base": "ComparisonSort",
-"class": "QuickSort",
-"language": "GDScript",
-"path": "res://levels/quick_sort.gd"
-}, {
-"base": "ComparisonSort",
 "class": "SelectionSort",
 "language": "GDScript",
 "path": "res://levels/selection_sort.gd"
@@ -62,7 +57,6 @@ _global_script_class_icons={
 "ComparisonSort": "",
 "InsertionSort": "",
 "MergeSort": "",
-"QuickSort": "",
 "SelectionSort": ""
 }
 

scripts/levels.gd

@@ -5,7 +5,6 @@ const LEVELS = [
     InsertionSort,
     SelectionSort,
     MergeSort,
-    QuickSort,
 ]
 var _level: ComparisonSort