LeetCode_Remove Duplicates from Sorted List II

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Remove Duplicates from Sorted List II

Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.
（移除链表中的重复元素（删除出现2次以上的元素））

Example:



1. 指针遍历

在遍历过程中维护一个 p_pre 来记录重复元素之前的位置。具体实现过程如下：

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class Solution:
    def deleteDuplicates(self, head: ListNode) -> ListNode:
        new_head = ListNode(0)
        new_head.next = head
        
        p_pre = new_head   
        p_cur = new_head.next
        while p_cur != None:
            while p_cur.next and p_cur.val == p_cur.next.val:
                p_cur = p_cur.next
            if p_pre.next == p_cur:
                p_pre = p_cur   
            else:
                p_pre.next = p_cur.next
            p_cur = p_cur.next 
        
        return new_head.next