feat(icake): add problem 8 superbalanced binary trees

Author: Jessica Yung

interview-cake/p8.py

@@ -0,0 +1,46 @@
+class BinaryTreeNode:
+    def __init__(self, value):
+        self.value = value
+        self.left = None
+        self.right = None
+
+    def insert_left(self, value):
+        self.left = BinaryTreeNode(value)
+        return self.left
+
+    def insert_right(self, value):
+        self.right = BinaryTreeNode(value)
+        return self.right
+
+
+def is_superbalanced(root):
+
+    # Initialise variables
+    max_depth = 1
+    min_depth = None
+    not_ended = []
+    for node in [root.left, root.right]:
+        if node is not None:
+            not_ended.append(node)
+
+    while not_ended is not None:
+        layer_nodes = not_ended
+
+        # Reset variables
+        ended = 0
+        not_ended = []
+
+        # Go through nodes in layer and check if any have ended
+        for node in layer_nodes:
+            if node.left is None and node.right is None:
+                ended += 1
+                if min_depth is None:
+                    min_depth = max_depth
+            else:
+                not_ended.append(node)
+
+        # Check if tree seems superbalanced so far
+        if max_depth - min_depth > 1:
+            return False
+
+    return True