Remove Duplicates from Sorted List II | Problems

Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers.

Example: head = [1,2,3,3,4,4,5] → [1,2,5]

Sample Input

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Sample Output

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Constraints

0 to 300 nodes
-100 <= Node.val <= 100
List is sorted

Topics

Linked List

Dummy Head + Skip Groups

function deleteDuplicates(head) {
  const dummy = {next: head};
  let prev = dummy;
  while (prev.next) {
    let curr = prev.next;
    while (curr.next && curr.val === curr.next.val) curr = curr.next;
    if (prev.next === curr) prev = prev.next;
    else prev.next = curr.next;
  }
  return dummy.next;
}

Time: O(n) | Space: O(1)

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