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Grokking the Coding Interview Patterns in Python

Solution: Swapping Nodes in a Linked List

Explore how to swap the values of the kth node from the start and end in a linked list by using three different in-place approaches: three-pass, two-pass, and one-pass. Understand the step-by-step algorithms to optimize time and space complexity while practicing linked list manipulation techniques useful for coding interviews.

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 kthk^{th} node from the start and the kthk^{th} node from the end in a singly linked list can be done using different methods. We’ll explore the three-pass, two-pass, and one-pass approaches in detail.

The three-pass approach

The three-pass approach uses two pointers to find and swap the ...