nth value from end in llist.py

# Given a pointer to the head of a linked list and a specific position, determine the data value at that position. Count backwards from the tail node. The tail is at postion 0, its parent is at 1 and so on.

# Example
#  refers to 

# Each of the data values matches its distance from the tail. The value  is at the desired position.

# Function Description

# Complete the getNode function in the editor below.

# getNode has the following parameters:

# SinglyLinkedListNode pointer head: refers to the head of the list
# int positionFromTail: the item to retrieve
# Returns

# int: the value at the desired position
# Input Format

# The first line contains an integer , the number of test cases.

# Each test case has the following format:
# The first line contains an integer , the number of elements in the linked list.
# The next  lines contains an integer, the data value for an element of the linked list.
# The last line contains an integer , the position from the tail to retrieve the value of.

# Constraints

# , where  is the  element of the linked list.



# import math
# import os
# import random
# import re
# import sys

# class SinglyLinkedListNode:
#     def __init__(self, node_data):
#         self.data = node_data
#         self.next = None

# class SinglyLinkedList:
#     def __init__(self):
#         self.head = None
#         self.tail = None

#     def insert_node(self, node_data):
#         node = SinglyLinkedListNode(node_data)

#         if not self.head:
#             self.head = node
#         else:
#             self.tail.next = node


#         self.tail = node

# def print_singly_linked_list(node, sep, fptr):
#     while node:
#         fptr.write(str(node.data))

#         node = node.next

#         if node:
#             fptr.write(sep)



def getNode(llist, positionFromTail):
    # Write your code here
    l = []
    while llist:
        l.append(llist.data)
        llist = llist.next
    return l[-positionFromTail-1]
  
  
# if __name__ == '__main__':
#     fptr = open(os.environ['OUTPUT_PATH'], 'w')

#     tests = int(input())

#     for tests_itr in range(tests):
#         llist_count = int(input())

#         llist = SinglyLinkedList()

#         for _ in range(llist_count):
#             llist_item = int(input())
#             llist.insert_node(llist_item)

#         position = int(input())

#         result = getNode(llist.head, position)

#         fptr.write(str(result) + '\n')

#     fptr.close()