LeetCode155|移除链表元素

示例:

输入: 1->2->6->3->4->5->6, val = 6
输出: 1->2->3->4->5

import java.util.*;

public class RemoveElementsTest3 {
    public static void main(String[] args) {
        ListNode l1 = new ListNode(1);
        ListNode l2 = new ListNode(2);
        ListNode l3 = new ListNode(6);
        ListNode l4 = new ListNode(3);
        ListNode l5 = new ListNode(4);
        ListNode l6 = new ListNode(5);
        ListNode l7 = new ListNode(6);
        l1.next = l2;
        l2.next = l3;
        l3.next = l4;
        l4.next = l5;
        l5.next = l6;
        l6.next = l7;
        ListNode listNode = removeElements2(l1, 6);
        System.out.println("listNode = " + listNode);

    }

    public static ListNode removeElements(ListNode head, int val) {
        ListNode dummyNode = new ListNode(0);
        ListNode currentNode = dummyNode;
        while (head != null) {
            if (head.val != val) {
                currentNode.next = head;
                currentNode = currentNode.next;
            }
            head = head.next;
        }
        currentNode.next = null;
        return dummyNode.next;
    }

    public static ListNode removeElements2(ListNode head, int val) {
        List<Integer> list = new LinkedList<>();
        while (head != null) {
            list.add(head.val);
            head = head.next;
        }
        List<Integer> tempList = new ArrayList<>();
        tempList.add(val);
        list.removeAll(tempList);
        ListNode dummyNode = new ListNode(0);
        ListNode tempNode = dummyNode;
        for (int i = 0, size = list.size(); i < size; i++) {
            ListNode listNode = new ListNode(list.get(i));
            tempNode.next = listNode;
            tempNode = tempNode.next;
        }
        return dummyNode.next;
    }
}