题解 | 链表的奇偶重排

# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None
#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 
# @param head ListNode类 
# @return ListNode类
#
class Solution:
    def oddEvenList(self , head: ListNode) -> ListNode:
        # write code here
        dummy_odd, dummy_even = ListNode(-1), ListNode(-1)#奇头节点，偶头节点
        odd, even = dummy_odd, dummy_even#奇当前节点，偶当前节点
        cur, n = head, 1#大连表当前节点，当前节点编号
        while cur:
            if n%2:#奇数位节点
                odd.next, odd, cur = cur, cur, cur.next
            else:#偶数位节点
                even.next, even, cur = cur, cur, cur.next
            n += 1#节点位数加一
        odd.next, even.next = dummy_even.next, None#奇偶位数链表进行拼接
        return dummy_odd.next#返回拼接后的链表