<p>You are given the <code>head</code> of a linked list.</p>

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

<p>Return <em>the </em><code>head</code><em> of the modified linked list.</em></p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2022/10/02/drawio.png" style="width: 631px; height: 51px;" />
<pre>
<strong>Input:</strong> head = [5,2,13,3,8]
<strong>Output:</strong> [13,8]
<strong>Explanation:</strong> 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.
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> head = [1,1,1,1]
<strong>Output:</strong> [1,1,1,1]
<strong>Explanation:</strong> Every node has value 1, so no nodes are removed.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li>The number of the nodes in the given list is in the range <code>[1, 10<sup>5</sup>]</code>.</li>
	<li><code>1 &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
</ul>

class Solution {
public:
    // Helper function to reverse the linked list
    ListNode* reverseList(ListNode* head) {
        ListNode* prev = nullptr;
        ListNode* curr = head;
        while (curr != nullptr) {
            ListNode* next = curr->next;
            curr->next = prev;
            prev = curr;
            curr = next;
        }
        return prev;
    }

    ListNode* removeNodes(ListNode* head) {
        if (!head || !head->next) return head;

        // Step 1: Reverse the linked list
        head = reverseList(head);

        // Step 2: Traverse the reversed list and remove nodes with smaller values
        ListNode* current = head;
        int maxVal = current->val;
        while (current != nullptr && current->next != nullptr) {
            if (current->next->val < maxVal) {
                // Remove the node since its value is smaller than the max seen so far
                ListNode* temp = current->next;
                current->next = temp->next;
                delete temp;
            } else {
                // Update max value and move to the next node
                maxVal = current->next->val;
                current = current->next;
            }
        }

        // Step 3: Reverse the list back to original order
        return reverseList(head);
    }
};

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