LeetCode #24: Swap Nodes in Pairs
β’ 61 words β’ 1 min β’ updated
LeetCode #24: Swap Nodes in Pairs:
python
# Definition for singly-linked list.
# class ListNode:
# def __init__(self, val=0, next=None):
# self.val = val
# self.next = next
class Solution:
def swapPairs(self, head: Optional[ListNode]) -> Optional[ListNode]:
if not head or not head.next:
return head
first = head
second = head.next
third = head.next.next
first.next = self.swapPairs(third)
second.next = first
return second