# Python - Insert a new node at a given position in the Circular Doubly Linked List

In this method, a new element is inserted at the specified position in the circular doubly linked list. For example - if the given list is 10->20->30 and a new element 100 is added at position 2, the list becomes 10->100->20->30.

First, create two nodes: 1. newNode with given element and 2. temp to traverse through the list. After that count the number of elements in the list to check whether the insertion position is valid or not (It must lie in the range of [1, n + 1], where n is number of elements in the list). If the insertion position is valid and equal to 1 then make the newNode as head and adjust links accordingly. If the insertion position is valid and greater than 1 then traverse to the specified position and insert the newNode and adjust links accordingly. The function push_at is created for this purpose. It is a 5-step process.

```def push_at(self, newElement, position):

#1. allocate node to new element and
#   create a temp node to traverse the list
newNode = Node(newElement)
NoOfElements = 0

#2. Find the number of elements in the list
if(temp != None):
NoOfElements += 1
temp = temp.next
NoOfElements += 1
temp = temp.next

#3. check if the insertion position is valid
if(position < 1 or position > (NoOfElements+1)):
print("\nInavalid position.")
elif (position == 1):

#4. if the position is 1, make next of the
else:
temp = temp.next
temp.next = newNode
newNode.prev = temp

else:

#5. Else, traverse to the node previous to
#   the given position, make newNode next
#   as temp next and temp next as newNode.
for i in range(1, position-1):
temp = temp.next
newNode.next = temp.next
newNode.next.prev = newNode
newNode.prev = temp
temp.next = newNode
```

The below is a complete program that uses above discussed concept to insert a new node at given position in the circular doubly linked list.

```# node structure
class Node:
def __init__(self, data):
self.data = data
self.next = None
self.prev = None

def __init__(self):

#Add new element at the end of the list
def push_back(self, newElement):
newNode = Node(newElement)
return
else:
temp = temp.next
temp.next = newNode
newNode.prev = temp

#Inserts a new element at the given position
def push_at(self, newElement, position):
newNode = Node(newElement)
NoOfElements = 0
if(temp != None):
NoOfElements += 1
temp = temp.next
NoOfElements += 1
temp = temp.next

if(position < 1 or position > (NoOfElements+1)):
print("\nInavalid position.")
elif (position == 1):
else:
temp = temp.next
temp.next = newNode
newNode.prev = temp

else:
for i in range(1, position-1):
temp = temp.next
newNode.next = temp.next
newNode.next.prev = newNode
newNode.prev = temp
temp.next = newNode

#display the content of the list
def PrintList(self):
if(temp != None):
print("The list contains:", end=" ")
while (True):
print(temp.data, end=" ")
temp = temp.next
break
print()
else:
print("The list is empty.")

# test the code

#Add three elements at the end of the list.
MyList.push_back(10)
MyList.push_back(20)
MyList.push_back(30)
MyList.PrintList()

#Insert an element at position 2
MyList.push_at(100, 2)
MyList.PrintList()

#Insert an element at position 1
MyList.push_at(200, 1)
MyList.PrintList()
```

The above code will give the following output:

```The list contains: 10 20 30
The list contains: 10 100 20 30
The list contains: 200 10 100 20 30
```

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