leetcode-ll

203. Remove Linked List Elements.py

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    """
    d->7->-7>-7->7
    perv cur
    """
    def removeElements(self, head: ListNode, val: int) -> ListNode:
        if not head:
            return head
        
        d = ListNode(-1)
        d.next = head
        prev = d
        cur = d.next
        while cur:
            if cur.val == val:
                prev.next = cur.next
            else:
                prev = prev.next
            cur = cur.next
        return d.next