题解 | #15.删除有序链表中重复的元素-I#

function deleteDuplicates( head ) {
  if(head==null || head.next==null)  
    return head;
  
  let cur = head;
  while(cur.next != null){
    if(cur.val == cur.next.val){
      cur.next = cur.next.next;
    }else{
      cur = cur.next;
    }
  }
  return head;
}

/*
 * function ListNode(x){
 *   this.val = x;
 *   this.next = null;
 * }
 */

/**
  * 
  * @param head ListNode类 
  * @return ListNode类
  */
 function deleteDuplicates( head ) {
  let empty = new ListNode(-100),
      pre = empty;
  
  while(head){
   if(head.val != pre.val){
     pre.next = head;
     pre = pre.next;
   }
    head = head.next;
  }
  
  pre.next = null;
  return empty.next;
}