# 01.11.2025 [3217. Delete Nodes From Linked List Present in Array]

Remove an array from linked list #medium #ll

01.11.2025

3217. Delete Nodes From Linked List Present in Array medium blog post substack youtube

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Problem TLDR

Remove an array from linked list #medium #ll

Intuition

Convert the array to HashSet.

Approach

• use a dummy node in a case of a removal of the first node from LL

• use a nested while loop

• code can be rewritten to a single while loop

Complexity

• Time complexity: $$O(n)$$

• Space complexity: $$O(n)$$

Code

// 47ms
    fun modifiedList(n: IntArray, h: ListNode?): ListNode? {
        val dummy = ListNode(0).apply { next = h }
        val s = n.toSet(); var curr = dummy
        while (curr.next != null)
            if (curr.next.`val` in s) curr.next = curr.next.next
            else curr = curr.next ?: break
        return dummy.next
    }

// 20ms
    pub fn modified_list(n: Vec<i32>, h: Option<Box<ListNode>>) -> Option<Box<ListNode>> {
        let mut dummy = ListNode { val: 0, next: h };
        let mut cur = &mut dummy;  let mut s: HashSet<_> = n.iter().collect();
        while let Some(next_box) = cur.next.as_mut() {
            if s.contains(&next_box.val) {
                cur.next = next_box.next.take();;
            } else { cur = cur.next.as_mut().unwrap() }
        }
        dummy.next
    }