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Solution: Swapping Nodes in a Linked List

Explore methods for swapping kth nodes from the beginning and end in a singly linked list. Learn three approaches—three-pass, two-pass, and one-pass—to perform in-place value swaps efficiently. Understand how to optimize traversals to achieve O(n) time complexity and O(1) space complexity. This lesson helps you master common in-place linked list manipulations useful in coding interviews.

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.
  • 11 \leq k \leq n 500\leq 500
  • 5000-5000 \leq Node.value 5000\leq 5000

Solution

Swapping the kth ...