Added very hard problem

Author: das-jishu

Very Hard/compare-leaf-traversal.py

@@ -0,0 +1,44 @@
+
+# COMPARE LEAF TRAVERSAL
+
+# This is an input class. Do not edit.
+class BinaryTree:
+    def __init__(self, value, left=None, right=None):
+        self.value = value
+        self.left = left
+        self.right = right
+
+# O(N + M) time and O(max(H1, H2)) space
+def compareLeafTraversal(tree1, tree2):
+    # Write your code here.
+	list1, _ = connectLeafNodes(tree1)
+	list2, _ = connectLeafNodes(tree2)
+	
+	current1 = list1
+	current2 = list2
+	while current1 is not None and current2 is not None:
+		if current1.value != current2.value:
+			return False
+		
+		current1 = current1.right
+		current2 = current2.right
+		
+	return current1 is None and current2 is None
+
+def connectLeafNodes(currentNode, head=None, previousNode=None):
+	if currentNode is None:
+		return head, previousNode
+	
+	if isLeafNode(currentNode):
+		if previousNode is None:
+			head = currentNode
+		else:
+			previousNode.right = currentNode
+			
+		previousNode = currentNode
+		
+	leftHead, leftPreviousNode = connectLeafNodes(currentNode.left, head, previousNode)
+	return connectLeafNodes(currentNode.right, leftHead, leftPreviousNode)
+
+def isLeafNode(node):
+	return node.left is None and node.right is None