206. Reverse Linked List

[w4irdo]

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution:
    def reverseList(self, head: ListNode) -> ListNode:
        """
        :type head: ListNode
        :rtype: ListNode
        """
        prev_node = None
        curr_node = head
        while curr_node:
            next_node = curr_node.next
            curr_node.next = prev_node
            prev_node = curr_node
            curr_node = next_node
        head = prev_node
        return head