Problem List

Remove Linked List Elements

May 31, 2025 • Go • linked list • easy

Problem

Given the head of a linked list and an integer val, remove all the nodes of the linked list that has Node.val == val, and return the new head.

Approach

1. Create a dummy node whose next value is the head
2. Iterate through the list with the head (curr) and set its next value to next.next or nil depending on the value of next
3. Return next.next

Performance

Runtime beats: 100%
Memory beats: 80%

Complexity

Time: O(n)
Space: O(n)

Go Solution

func removeElements(head *ListNode, val int) *ListNode {
	dummy := &ListNode{Val: 0, Next: head}
	curr := dummy

	if curr == nil {
		return nil
	}

	for curr != nil {
		for curr.Next != nil && curr.Next.Val == val {
			if curr.Next != nil {
				curr.Next = curr.Next.Next
			} else {
				curr.Next = nil
			}
		}
        curr = curr.Next
	}

	return dummy.Next
}

LeetCode Problem Link