# Definition for singly-linked list. # class ListNode(object): # def __init__(self, x): # self.val = x # self.next = None class Solution(object): def reorderList(self, head): """ :type head: ListNode :rtype: void Do not return anything, modify head in-place instead. """ if not head: return temp = head slow = head fast = head while fast and fast.next: fast = fast.next.next slow = slow.next if fast: slow = slow.next stack =  while slow: stack.append(slow) slow = slow.next slow = head while stack: temp = slow.next node = stack.pop() slow.next = node node.next = temp slow = temp slow.next = None
Python solution using Stack
Looks like your connection to LeetCode Discuss was lost, please wait while we try to reconnect.