82. Remove Duplicates from Sorted List II

题目82. Remove Duplicates from Sorted List II

Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.
For example,
Given 1->2->3->3->4->4->5, return 1->2->5.
Given 1->1->1->2->3, return 2->3.

1

public class Solution {
    public ListNode deleteDuplicates(ListNode head) {
        if(head == null || head.next == null){
            return head;
        }
        
        ListNode tempHead = new ListNode(1);
        tempHead.next = head;
        ListNode preHeadNode = tempHead;
        int val = head.val;
        int count = 1;
        ListNode node = head.next;
        while(node != null){
            if(node.val == val){
                count++;
            }else{
                if(count == 1){
                    preHeadNode = preHeadNode.next;
                }else{
                    preHeadNode.next = node;
                }
                val = node.val;
                count = 1;
            }
            node = node.next;
        }
        if(count != 1){
            preHeadNode.next = null;
        }
        return tempHead.next;
    }
}