LeetCode-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.

public ListNode deleteDuplicates(ListNode head) {        ListNode root = new ListNode(0);        root.next = head;        head = root;        while (root.next != null) {        int val = root.next.val;        ListNode pNode = root.next.next;        while (pNode != null) {        if (val != pNode.val) {        break;        }        pNode = pNode.next;        }        if (pNode == root.next.next) {        root = root.next;        } else {        root.next = pNode;        }        }        return head.next;    }