fix: bubble sort no longer fails on reversed array

A corner case in the end condition of bubble sort meant that if the
array ever got to a state where the unsorted subarray is size 2 and out
of order, i.e. _end = 2 AND array[0] > array[1] (starting with a
reversed array will lead to this condition), the next iteration will
have _index  equal _end, missing the end condition entirely and
eventually causing a crash when the player goes outside the array
bounds.

Author: danielzting

levels/bubble_sort.gd

@@ -32,7 +32,7 @@ func next(action):
     _index += 1
     # Prevent player from having to spam tap through the end
     if _index + 1 == _end:
-        if not _swapped:
+        if not _swapped or _end == 2: # Stop if only one element left
             emit_signal("done")
         _index = 0
         _end -= 1

models/array_model.gd

@@ -9,7 +9,7 @@ func _init(size=16):
     for i in range(1, size + 1):
         array.append(i)
     array.shuffle()
-    self.size = size
+    self.size = array.size()
 
 func at(i):
     """Retrieve the value of the element at index i."""