feat: add odd-even sort

Author: danielzting

levels/odd_even_sort.gd

@@ -0,0 +1,42 @@
+"""
+ODD-EVEN SORT
+
+Odd-even sort is a variant of bubble sort that alternates on elements at
+odd and even indices.
+
+If the two highlighted elements are out of order, hit LEFT ARROW to swap
+them. Otherwise, hit RIGHT ARROW to continue.
+"""
+
+class_name OddEvenSort
+extends ComparisonSort
+
+const ACTIONS = {
+    "SWAP": "Left",
+    "CONTINUE": "Right",
+}
+var _index = 1
+var _swapped = false
+
+func _init(array).(array):
+    pass
+
+func next(action):
+    if array.at(_index) > array.at(_index + 1):
+        if action != null and action != ACTIONS.SWAP:
+            return emit_signal("mistake")
+        array.swap(_index, _index + 1)
+        _swapped = true
+    elif action != null  and action != ACTIONS.CONTINUE:
+        return emit_signal("mistake")
+    _index += 2
+    if _index + 1 >= array.size:
+        if _index % 2 == 0 and not _swapped:
+            emit_signal("done")
+        _index = 1 if _index % 2 == 0 else 0
+        _swapped = false
+
+func get_effect(i):
+    if i == _index or i == _index + 1:
+        return EFFECTS.HIGHLIGHTED
+    return EFFECTS.NONE

project.godot

@@ -65,6 +65,11 @@ _global_script_classes=[ {
 "path": "res://levels/merge_sort.gd"
 }, {
 "base": "ComparisonSort",
+"class": "OddEvenSort",
+"language": "GDScript",
+"path": "res://levels/odd_even_sort.gd"
+}, {
+"base": "ComparisonSort",
 "class": "QuickSort",
 "language": "GDScript",
 "path": "res://levels/quick_sort.gd"
@@ -91,6 +96,7 @@ _global_script_class_icons={
 "CycleSort": "",
 "InsertionSort": "",
 "MergeSort": "",
+"OddEvenSort": "",
 "QuickSort": "",
 "SelectionSort": "",
 "ShellSort": ""

scripts/levels.gd

@@ -10,6 +10,7 @@ const LEVELS = [
     ShellSort,
     CombSort,
     CycleSort,
+    OddEvenSort,
 ]
 const MIN_WAIT = 1.0 / 32 # Should be greater than maximum frame time
 const MAX_WAIT = 4