删除链表结点的两种解法

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/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class Solution {
    public ListNode deleteNode(ListNode head, int val) {
        if(head == null) return null;
        if(head.val == val) return head.next;
        else head.next = deleteNode(head.next,val);
        return head;

    }
}
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class Solution {
    public ListNode deleteNode(ListNode head, int val) {
        ListNode pre = head;
        ListNode cur = head.next;
        
        if (head.val == val)  return head.next;

        while (cur != null) {
            if (cur.val == val) {
                pre.next = cur.next;
            }
            pre = cur;
            cur = cur.next;

        }
        return head;
    }
}