class Node:
    def __init__(self,val=0,next=None,prev=None):
        self.val = val
        self.next = next
        self.prev = prev

node = Node(100)

def to_dll(nums):
    if not nums:
        return None

    head = Node(nums[0])
    temp = head
    for num in nums[1:]:
        temp.next = Node(num,prev=temp)
        temp = temp.next

    return head

def from_dll(head):
    result = []
    temp = head
    
    while temp is not None:
        result.append(temp.val)
        temp = temp.next

    return result

print(from_dll(to_dll([1,2,3,4,5])))

[1, 2, 3, 4, 5]

DLL: 1 <-> 2 <-> 3 <-> 4
Value to be Inserted: 6
Result: DLL: 1 <-> 2 <-> 3 <-> 4 <-> 6

DLL: 10 <-> 20 <-> 30
Value to be Inserted: 40
Result: DLL: 10 <-> 20 <-> 30 <-> 40

def insert_end(dll,val):
    if dll is None:
        return Node(val)

    temp = dll
    while temp.next is not None:
        temp = temp.next
    
    temp.next = Node(val,prev=temp)

    return dll



print(from_dll(insert_end(to_dll([1,2,3,4]),6)))
print(from_dll(insert_end(to_dll([10,20,30]),40)))

[1, 2, 3, 4, 6]
[10, 20, 30, 40]

Lecture 2 (Learn Doubly Linked List)¶

Create a Node¶

Convert a list into doubly linked list¶

Convert dll to list¶

Insert at end of Doubly Linked List¶

Approach 1¶

Complexity¶