LeetCode (8) - Odd Even Linked List(파이썬, python)

❓ 문제

Given the head of a singly linked list, group all the nodes with odd indices together followed by the nodes with even indices, and return the reordered list.

The first node is considered odd, and the second node is even, and so on.

Note that the relative order inside both the even and odd groups should remain as it was in the input.

You must solve the problem in O(1) extra space complexity and O(n) time complexity.

Example 1:

Input: head = [1,2,3,4,5]
Output: [1,3,5,2,4]

Example 2:

Input: head = [2,1,3,5,6,4,7]
Output: [2,3,6,7,1,5,4]

Constraints:

• n == number of nodes in the linked list
• 0 <= n <= 104
• -106 <= Node.val <= 106

---

Given Code

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

---

내 풀이

class Solution:
    def oddEvenList(self, head):

        odd = None
        even = None

        idx = 0
        tmp = head
        while(tmp != None):
            if idx % 2 == 0:
                odd = ListNode(tmp.val, odd)
            elif idx % 2 == 1:
                even = ListNode(tmp.val, even)
            tmp = tmp.next
            idx += 1

        res = None
        while(even != None):
            res = ListNode(even.val, res)
            even = even.next
        while(odd != None):
            res = ListNode(odd.val, res)
            odd = odd.next

        return res