Create Flattening_List.py

Author: CaptainAshwin

Diff for: Flattening_List.py

@@ -0,0 +1,119 @@
+# Python program for flattening a Linked List
+
+class Node():
+	def __init__(self,data):
+		self.data = data
+		self.right = None
+		self.down = None
+
+class LinkedList():
+	def __init__(self):
+
+		# head of list
+		self.head = None
+
+	# Utility function to insert a node at beginning of the
+	# linked list
+	def push(self,head_ref,data):
+
+		# 1 & 2: Allocate the Node &
+		# Put in the data
+		new_node = Node(data)
+
+		# Make next of new Node as head
+		new_node.down = head_ref
+
+		# 4. Move the head to point to new Node
+		head_ref = new_node
+
+		# 5. return to link it back
+		return head_ref
+
+	def printList(self):
+
+		temp = self.head
+		while(temp != None):
+			print(temp.data,end=" ")
+			temp = temp.down
+
+		print()
+
+	# An utility function to merge two sorted linked lists
+	def merge(self, a, b):
+		# if first linked list is empty then second
+		# is the answer
+		if(a == None):
+			return b
+		
+		# if second linked list is empty then first
+		# is the result
+		if(b == None):
+			return a
+
+		# compare the data members of the two linked lists
+		# and put the larger one in the result
+		result = None
+
+		if (a.data < b.data):
+			result = a
+			result.down = self.merge(a.down,b)
+		else:
+			result = b
+			result.down = self.merge(a,b.down)
+
+		result.right = None
+		return result
+
+	def flatten(self, root):
+
+		# Base Case
+		if(root == None or root.right == None):
+			return root
+		# recur for list on right
+
+		root.right = self.flatten(root.right)
+
+		# now merge
+		root = self.merge(root, root.right)
+
+		# return the root
+		# it will be in turn merged with its left
+		return root
+
+# Driver program to test above functions
+L = LinkedList()
+
+'''
+Let us create the following linked list
+			5 -> 10 -> 19 -> 28
+			| |	 |	 |
+			V V	 V	 V
+			7 20 22 35
+			|		 |	 |
+			V		 V	 V
+			8		 50 40
+			|			 |
+			V			 V
+			30			 45
+'''
+L.head = L.push(L.head, 30);
+L.head = L.push(L.head, 8);
+L.head = L.push(L.head, 7);
+L.head = L.push(L.head, 5);
+
+L.head.right = L.push(L.head.right, 20);
+L.head.right = L.push(L.head.right, 10);
+
+L.head.right.right = L.push(L.head.right.right, 50);
+L.head.right.right = L.push(L.head.right.right, 22);
+L.head.right.right = L.push(L.head.right.right, 19);
+
+L.head.right.right.right = L.push(L.head.right.right.right, 45);
+L.head.right.right.right = L.push(L.head.right.right.right, 40);
+L.head.right.right.right = L.push(L.head.right.right.right, 35);
+L.head.right.right.right = L.push(L.head.right.right.right, 20);
+
+# flatten the list
+L.head = L.flatten(L.head);
+
+L.printList()