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| class Solution {
public ListNode removeNodes(ListNode head) {
Stack<ListNode> decreaseStack = new Stack<>();
ListNode curr = head;
while (curr != null) {
while (!decreaseStack.isEmpty() && curr.val > decreaseStack.peek().val) {
decreaseStack.pop();
}
decreaseStack.push(curr);
curr = curr.next;
}
ListNode next = null;
while (!decreaseStack.isEmpty()) {
ListNode node = decreaseStack.pop();
node.next = next;
next = node;
}
return next;
}
}
|
Stack
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| class Solution {
public ListNode removeNodes(ListNode head) {
Stack<ListNode> decreaseStack = new Stack<>();
ListNode sentinel = new ListNode(Integer.MAX_VALUE);
decreaseStack.push(sentinel);
ListNode curr = head;
while (curr != null) {
while (!decreaseStack.isEmpty() && curr.val > decreaseStack.peek().val) {
decreaseStack.pop();
}
decreaseStack.peek().next = curr;
decreaseStack.push(curr);
curr = curr.next;
}
return sentinel.next;
}
}
|
References
2487. Remove Nodes From Linked List