203. 移除链表元素

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 。

示例 1:

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：[]

复杂度

虚拟头结点

• 时间复杂度：\(O(n)\)
• 空间复杂度：\(O(1)\)

题解

Go

/**
 * Definition for singly-linked list.
 * type ListNode struct {
 *     Val int
 *     Next *ListNode
 * }
 */
func removeElements(head *ListNode, val int) *ListNode {
    dummyHead := &ListNode{}
    dummyHead.Next = head
    cur := dummyHead
    for cur != nil && cur.Next != nil {
        if cur.Next.Val == val {
            cur.Next = cur.Next.Next
        } else {
            cur = cur.Next
        }
    }
    return dummyHead.Next
}

Python

# 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]:
        # 创建虚拟头部节点以简化删除过程
        dummy_head = ListNode(next = head)

        # 遍历列表并删除值为val的节点
        current = dummy_head
        while current.next:
            if current.next.val == val:
                current.next = current.next.next
            else:
                current = current.next

        return dummy_head.next