data-structures-and-algorithms

401 data structures and algorithms code challenges

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Data Structures and Algorithms

Language: Python

Linked Lists Kth

Feature Tasks

k-th value from the end of a linked list.

Write the following method for the Linked List class:

• kth from end
  • argument: a number, k, as a parameter.
  • Return the node’s value that is k places from the tail of the linked list.
  • You have access to the Node class and all the properties on the Linked List class as well as the methods created in previous challenges.

Whiteboard Process

Examples

ll.kthFromEnd(k)

Input ll	Arg k	Output
head -> [1] -> [3] -> [8] -> [2] -> X	0	2
head -> [1] -> [3] -> [8] -> [2] -> X	2	3
head -> [1] -> [3] -> [8] -> [2] -> X	6	Exception

Unit Tests

Write tests for the following scenarios, and any other cases:

1. Where k is greater than the length of the linked list
2. Where k and the length of the list are the same
3. Where k is not a positive integer
4. Where the linked list is of a size 1
5. “Happy Path” where k is not at the end, but somewhere in the middle of the linked list

Stretch Goal

Implement a method that finds the node at the middle of the Linked List.

Approach & Efficiency