[Python] Leetcode 206. Reverse Linked List
Leetcode 206. Reverse Linked List
문제
Given the head of a singly linked list, reverse the list, and return the reversed list.
풀이
- Linked List 자료구조가 익숙하지 않음. 인풋 형식을 주석으로 첨부함.
# class ListNode:
# def __init__(self, val=0, next=None):
# self.val = val
# self.next = next
# node4 = ListNode(4)
# node3 = ListNode(3, node4)
# node2 = ListNode(2, node3)
# node1 = ListNode(1, node2)
class Solution:
def reverseList(self, head: Optional[ListNode]) -> Optional[ListNode]:
node = head
my_stack = []
while node: # [node1, node2, node3, node4]
my_stack.append(node)
node = node.next
dummy = ListNode(-1)
node = dummy
while my_stack: # [node4, node3, node2, node1]
node.next = my_stack.pop()
node = node.next # dummy -> node4 -> node3 -> node2 -> node1
node.next = None # node1 -> none
return dummy.next
