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# Runtime: 151 ms (Top 10.13%) | Memory: 17.7 MB (Top 81.63%)
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# Definition for singly-linked list.
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# class ListNode:
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# def __init__(self, val=0, next=None):
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# self.val = val
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# self.next = next
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class Solution:
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    def removeElements(self, head: Optional[ListNode], val: int) -> Optional[ListNode]:
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        prev = head
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        cur = head
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        while cur is not None:
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            if cur.val == val:
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                if cur == head:
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                    head = head.next
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                    prev = head
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                else:
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                    prev.next = cur.next
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            else:
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                prev = cur
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            cur = cur.next
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        return head