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Grokking the Coding Interview Patterns in Python

Solution: Swapping Nodes in a Linked List

Explore how to swap the kth node from the beginning with the kth node from the end in a singly linked list. This lesson covers three approaches — one-pass, two-pass, and three-pass methods — to perform this in-place operation efficiently, helping you understand pointer manipulation and linked list traversal strategies.

We'll cover the following...

Statement

Given the head of a linked list and an integer, k, return the head of the linked list after swapping the values of the kthk^{th} node from the beginning and the kthk^{th} node from the end of the linked list.

Note: We’ll number the nodes of the linked list starting from 11 to nn.

Constraints:

  • The linked list will have n number of nodes.
  • 1≤1 \leq k ≤\leq n ≤500\leq 500
  • −5000≤-5000 \leq Node.value ≤5000\leq 5000

Solution

Swapping the kth ...