[leetcode 24] Swap Nodes in Pairs

LeetCode-24

swap-nodes-in-pairs : Given a linked list, swap every two adjacent nodes and return its head. You must solve the problem without modifying the values in the list's nodes

note : only nodes themselves may be changed.

MyAnswer

        :::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]:
        now = head
        while now and now.next:
            now.val, now.next.val = now.next.val, now.val
            now = now.next.next
        return head

Result : 36ms Memory: 13.8mb