Program to add a new node at the middle of the singly linked list cod…

addnodeatmiddleSLL.py

@@ -0,0 +1,78 @@
+# Python3 implementation to insert node
+# at the middle of a linked list
+
+# Node class
+class Node:
+
+	# constructor to create a new node
+	def __init__(self, data):
+		self.data = data
+		self.next = None
+
+# function to insert node at the
+# middle of linked list given the head
+def insertAtMid(head, x):
+
+	if(head == None): #if the list is empty
+		head = Node(x)
+	else:
+
+		# create a new node for the value
+		# to be inserted
+		newNode = Node(x)
+
+		ptr = head
+		length = 0
+
+		# calculate the length of the linked
+		# list
+		while(ptr != None):
+			ptr = ptr.next
+			length += 1
+
+		# 'count' the number of node after which
+		# the new node has to be inserted
+		if(length % 2 == 0):
+			count = length / 2
+		else:
+			(length + 1) / 2
+
+		ptr = head
+
+		# move ptr to the node after which
+		# the new node has to inserted
+		while(count > 1):
+			count -= 1
+			ptr = ptr.next
+
+		# insert the 'newNode' and adjust
+		# links accordingly
+		newNode.next = ptr.next
+		ptr.next = newNode
+
+# function to display the linked list
+def display(head):
+	temp = head
+	while(temp != None):
+		print(str(temp.data), end = " ")
+		temp = temp.next
+
+# Driver Code
+
+# Creating the linked list 1.2.4.5
+head = Node(1)
+head.next = Node(2)
+head.next.next = Node(4)
+head.next.next.next = Node(5)
+
+print("Linked list before insertion: ", end = "")
+display(head)
+
+# inserting 3 in the middle of the linked list.
+x = 3
+insertAtMid(head, x)
+
+print("\nLinked list after insertion: " , end = "")
+display(head)
+
+# This code is contributed by Pranav Devarakonda