143. Reorder List
Medium
30 Points
Linked List
Two Pointers
Stack
Recursion
You are given the head of a singly linked-list. The list can be represented as:
Reorder the list to be on the following form:
You may not modify the values in the list's nodes. Only nodes themselves may be changed.
Examples
Example 1
L0 → L1 → … → Ln - 1 → Ln
Example 2
L0 → Ln → L1 → Ln - 1 → L2 → Ln - 2 → …
Example 3
Input: head = [1,2,3,4]
Output: [1,4,2,3]
Example 4
Input: head = [1,2,3,4,5]
Output: [1,5,2,4,3]
Constraints
The number of nodes in the list is in the range [1, 5 * 104].1 <= Node.val <= 1000
143. Reorder List
Medium
30 Points
Linked List
Two Pointers
Stack
Recursion
You are given the head of a singly linked-list. The list can be represented as:
Reorder the list to be on the following form:
You may not modify the values in the list's nodes. Only nodes themselves may be changed.
Examples
Example 1
L0 → L1 → … → Ln - 1 → Ln
Example 2
L0 → Ln → L1 → Ln - 1 → L2 → Ln - 2 → …
Example 3
Input: head = [1,2,3,4]
Output: [1,4,2,3]
Example 4
Input: head = [1,2,3,4,5]
Output: [1,5,2,4,3]
Constraints
The number of nodes in the list is in the range [1, 5 * 104].1 <= Node.val <= 1000