#24

Swap Nodes in Pairs

pupil · 570 · lc medium +29 · 69% accepted · 13,084 likes · top 76%

Description

Exchange every pair of adjacent nodes in the linked list and return the new head. Only node pointers may be rearranged; node values must not be modified.

Code

# 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]:

# 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]: