【链表】剑指offer18：删除链表指定节点

力扣，https://leetcode.cn/problems/shan-chu-lian-biao-de-jie-dian-lcof/description/

Python

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def deleteNode(self, head: Optional[ListNode], val: int) -> Optional[ListNode]:
        pre, cur = ListNode(-1), head
        pre.next = cur
        while cur:
            if cur.val == val:
                pre.next = cur.next
                if cur == head:
                    return pre.next
                break
            pre = cur
            cur = cur.next
        return head

Java

// 自己写的答案
class Solution {
    public ListNode deleteNode(ListNode head, int val) {
        if (head == null) {
            return null;
        }
        if (head.val == val) {
            return head.next;
        }
        ListNode pre = head, cur = head.next;
        while (cur != null) {
            if (cur.val != val) {
                pre = cur;
                cur = cur.next;
            } else {
                pre.next = cur.next;
                break;
            }
        }

        return head;
    }
}