Power button - 203 - remove the list elements linked list

Title description

Give you the head node of the linked list head and an integer val, please delete all the nodes in the linked list that satisfy Node.val == val, and returns the new head node .

Solution ideas

• Because the element to be deleted may be at the head of the linked list, it is necessary to add a virtual node to the head in front of the head of the linked list

Input and output example

Code

/*** Definition for singly-linked list.* public class ListNode {* int val;*ListNode next;* ListNode() {}* ListNode(int val) { this.val = val; }* ListNode(int val, ListNode next) { this.val = val; this.next = next; }* }*/class Solution {public ListNode removeElements(ListNode head, int val) {if(head == null){return head;}ListNode dummy = new ListNode(-1,head);ListNode pre = dummy;ListNode cur = head;while(cur != null){if(cur.val == val){pre.next = cur.next;}else{pre = cur;}cur = cur.next;}return dummy.next;}}