[LeetCode 75] Medium - 328. Odd Even Linked List

328. Odd Even Linked List

 

# 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]:
        # 노드가 2개 까지는 그대로 반환
        if not head or not head.next or not head.next.next: 
            return head

        odd = current = head  # 홀수
        even = even_head = head.next  # 짝수
        i = 1

        while current:

            if i>2 and i % 2 == 1: # 홀수
                odd.next = current
                odd = odd.next
            elif i>2 and i % 2 == 0:  # 짝수번째              
                even.next = current
                even = even.next

            current = current.next
            i +=1

        odd.next = even_head
        even.next = None
        return head

 

https://youtu.be/LCQb5dOScFM?si=bQLSKYOH2QP45P2p