203-RemoveLinkedListElements

Remove Linked List Elements

Problem can be found in here!

# Definition for singly-linked list.
class ListNode:
    def __init__(self, val=0, next=None):
        self.val = val
        self.next = next

Solution: Two Pointers

def removeElements(head: Optional[ListNode], val: int) -> Optional[ListNode]:
    if not head:
        return head

    dummy_head = previous_node = ListNode(0, head)
    while head:
        if head.val != val:
            previous_node = head
        else:
            previous_node.next = head.next
        head = head.next

    return dummy_head.next

Time Complexity: , Space Complexity: .