#1721

Swapping Nodes in a Linked List

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Description

Given the head of a linked list and an integer k (1-indexed), swap the values of the kth node from the beginning and the kth node from the end. Return the head of the modified list.

Example 1:

Input: head = [1,2,3,4,5], k = 2

Output: [1,4,3,2,5]

Example 2:

Input: head = [7,9,6,6,7,8,3,0,9,5], k = 5

Output: [7,9,6,6,8,7,3,0,9,5]

Code

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def swapNodes(self, head: Optional[ListNode], k: int) -> Optional[ListNode]:

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def swapNodes(self, head: Optional[ListNode], k: int) -> Optional[ListNode]: