力扣:203. 移除链表元素(Python3)

题目:

给你一个链表的头节点 head 和一个整数 val ,请你删除链表中所有满足 Node.val == val 的节点,并返回 新的头节点 。

来源:力扣(LeetCode)
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示例:

示例 1:

力扣:203. 移除链表元素(Python3)_第1张图片

输入:head = [1,2,6,3,4,5,6], val = 6
输出:[1,2,3,4,5]


示例 2:

输入:head = [], val = 1
输出:[]


示例 3:

输入:head = [7,7,7,7], val = 7
输出:[]

解法:

转为列表,循环删除指定元素,再转成链表。

代码:

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def removeElements(self, head: Optional[ListNode], val: int) -> Optional[ListNode]:
        nums = []
        while head:
            nums.append(head.val)
            head = head.next
        while val in nums:
            nums.remove(val)
        head = point = ListNode(-1)
        for num in nums:
            point.next = ListNode(num)
            point = point.next
        return head.next

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