Solution.cpp

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */
class Solution {
public:
    ListNode* removeNodes(ListNode* head) {
        vector<int> nums;
        while (head) {
            nums.emplace_back(head->val);
            head = head->next;
        }
        vector<int> stk;
        for (int v : nums) {
            while (!stk.empty() && stk.back() < v) {
                stk.pop_back();
            }
            stk.push_back(v);
        }
        ListNode* dummy = new ListNode();
        head = dummy;
        for (int v : stk) {
            head->next = new ListNode(v);
            head = head->next;
        }
        return dummy->next;
    }
};