206 - Reverse Linked List

Details

Key	Value
Link	https://leetcode.com/problems/reverse-linked-list/
Language	Python 3
Runtime	54 ms, faster than 48.90% of Python3 online submissions for Reverse Linked List
Memory Usage	15.4 MB, less than 55.56% of Python3 online submissions for Reverse Linked List
Datastructures	ListNode (linked list)
Algorithms	Iterative
Complexity	Time: O(n) Space: O(1)

Procedure

1. ...

Code

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