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.
/**
* 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) {
stack<ListNode *> st;
while(head->next != nullptr){
st.push(head);
head = head->next;
}
while(!st.empty()){
if(st.top()->val >=head->val||head==nullptr){
st.top()->next = head;
head = st.top();
}
st.pop();
}
return head;
}
};
