From LeetCode 203. Remove Linked List Elements
Description
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.
Example 1:
Input: head = [1,2,6,3,4,5,6], val = 6
Output: [1,2,3,4,5]
Example 2:
Input: head = [], val = 1
Output: []
Example 3:
Input: head = [7,7,7,7], val = 7
Output: []
Solutions
When we delete a node, we usually will let pointer point to the next node. But what if we want to delete the head node? We can move head node to the next.
def removeElements(self, head: ListNode, val: int) -> ListNode:
dummy_head = ListNode(next=head) # add a dummy head
cur = dummy_head
while(cur.next!=None):
if(cur.next.val == val):
cur.next = cur.next.next #delete cur.next.next node
else:
cur = cur.next
return dummy_head.next