Delete n-th element from the last : Singly linked list

deleteKthFromLast.py

#   ////////////////////////////////////////////////////
#  --------Deleting n-th element from last-------------
# ////////////////////////////////////////////////////

'''
Logic :

    Suppose we have a linked list  1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7 -> 8 -> 9 -> 0
    And we were ask to delete 6th element from last, which is '5'

    We traverse the linked list till 6th element of list, which is '6'

    If 6th element is None then we will delete 1st element, which is 1
    But in our case it is not none.
    So we take a new pointer (k) which will point to root 
    our previous pointer (j) is at elemment '7' 

    1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7 -> 8 -> 9 -> 0
    k                             j

    Now we will move both pointer 1 ahead and 
    continue till j reaches last element, which is '0'

    So,
    
    1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7 -> 8 -> 9 -> 0
         k                             j

    1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7 -> 8 -> 9 -> 0
              k                             j

    1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7 -> 8 -> 9 -> 0
                   k                             j


    Automatically k will be at (n + 1) element from the last.
    So we simply delete the nth element from the last

  Uncomment code to see changes in linked list
'''

# Node class

class Node:
    def __init__(self, value):
        self.data = value
        self.next = None
    
    def setNext(self,next):
        self.next = next
    
    def getNext(self):
        return self.next
    
    def getData(self):
        return self.data

    def setData(self, data):
        self.data = data

# Making a liked list
node = Node(1)                  # root node
last = node                     # last node
item = [2,3,4,5,6,7,8,9,0]      # items to be inserted
for i in item:
    last.setNext(Node(i))
    last = last.getNext()


# print('-----------Items Before deleting-----------------')
# new_node = node
# while new_node is not None:
#     print(new_node.getData())
#     new_node = new_node.getNext()
# print('-------------------------------------------------')



# delete method
def deleteFromLast(node,k):
    node_1 = node
    count = 1
    while count <= k and node_1 is not None:
        node_1 = node_1.getNext()
        count += 1
    value = None
    if count < k+1:
        return "Index out of bound"
    if node_1 is None:
        value = node.getData()
        node.setData(node.getNext().getData())
        node.setNext(node.getNext().getNext())
        return value
    node_2 = node
    while node_1.getNext() is not None:
        node_1 = node_1.getNext()
        node_2 = node_2.getNext()
    value = node_2.getNext().getData()
    node_2.setNext(node_2.getNext().getNext())
    return value

  
# testing --

print("Result : " , deleteFromLast(node,6))

# print('-----------Items After deleting-----------------')
# new_node = node
# while new_node is not None:
#     print(new_node.getData())
#     new_node = new_node.getNext()
# print('-------------------------------------------------')