2487. Remove Nodes From Linked List

[mah-shamim]

Topics: Linked List, Stack, Recursion, Monotonic Stack, Weekly Contest 321

You are given the head of a linked list.

Remove every node which has a node with a greater value anywhere to the right side of it.

Return the head of the modified linked list.

Example 1:

• Input: head = [5,2,13,3,8]
• Output: [13,8]
• Explanation: The nodes that should be removed are 5, 2 and 3.
  • Node 13 is to the right of node 5.
  • Node 13 is to the right of node 2.
  • Node 8 is to the right of node 3.

Example 2:

• Input: head = [1,1,1,1]
• Output: [1,1,1,1]
• Explanation: Every node has value 1, so no nodes are removed.

Constraints:

• The number of the nodes in the given list is in the range [1, 105].
• 1 <= Node.val <= 105

Hint:

1. Iterate on nodes in reversed order.
2. When iterating in reversed order, save the maximum value that was passed before.