题解 | #删除链表中重复的结点#

import java.util.*;
/*
 public class ListNode {
    int val;
    ListNode next = null;

    ListNode(int val) {
        this.val = val;
    }
}
*/
public class Solution {
  public  ListNode deleteDuplication(ListNode pHead) {
        Set<Integer> set = new HashSet<>();
        ListNode cur = pHead;
        while (cur != null) {
            if (set.contains(cur.val)) {//存在就删除 但是set中储存的并没哟删除
                pHead = del(pHead, cur.val);//一次就会把所有相同的给删除
            } else {
                set.add(cur.val);
            }
            cur = cur.next;
        }
        return pHead;
    }

    public  ListNode del(ListNode node, int val) {
        ListNode cur = node;
        ListNode prev = node;
        while (cur != null) {
            if (cur == node && cur.val == val) {
                cur = cur.next;
                prev = node = cur;
            } else if (cur.val == val) {//删除
                prev.next = cur.next;
                cur = cur.next;
            } else {
                prev = cur;
                cur = cur.next;
            }
        }
        return node;
    }
}