题解 | #删除链表中重复的结点#

用一个set查重，循环链表进行节点删除，在set里就是重的。

/*
 public class ListNode {
    int val;
    ListNode next = null;

    ListNode(int val) {
        this.val = val;
    }
}
*/
import java.util.*;
public class Solution {
    public ListNode deleteDuplication(ListNode pHead) {
        ListNode p1,p2,head = pHead;
        p2 = pHead;
        Set<Integer> we = new HashSet<>();
        if(pHead == null){
            return null;
        }
        if(pHead.next == null){
            return pHead;
        }
        while(p2 !=null){
            if(p2.next != null){
                if(p2.next.val == p2.val){
                    we.add(p2.val);
                }
            }
            p2 = p2.next;
        }
        p2 = null;
        
        p1 = head.next;
        
        if(head.next.next != null){
            p2 = head.next.next;
        }
        
        while(p2 != null && p1 != null){
            if(we.contains(p1.val)){
                head.next = p2;
                p1 = p2;
                p2 = p2.next;
            }else{
                head = p1;
                p1 = p2;
                p2 = p2.next;
            }
        }
        if(we.contains(p1.val)){
            head.next = null;
        }
        if(we.contains(pHead.val)){
            pHead = pHead.next;
        }
        
        return pHead;
    }
}