链表oj----移除链表元素

Posted 2021-11-09 ohana！

题目内容：

方法一：（把空链表和若要删除的是头节点，单独拿出来判断）

if(head == null){
   return null;
}

ListNode prev = head;
ListNode cur = head.next;

while(cur != null){
   if(cur.val == val){
        prev.next = cur.next;
        cur = cur.next;
   }else{
        prev = cur;
        cur = cur.next;
   }
}
if(head.val == val){
     head = head.next;
  }
return head;

方法二：（把只需要把链表是否为空进行判断）（逻辑性强）

    if(head == null){
        return head;
    }
    ListNode cur = head;
    ListNode prev = null;

    while(cur != null){
        if (cur.val == val){
            //删除节点
            if (head.val == val){   //删除头节点
                head = head.next;
                cur = head;
            }else{                  //删除非头节点
                prev.next = cur.next;
                cur = prev.next;
            }
        }else{
            //不删除节点
            prev = cur;
            cur = cur.next;
        }
    }

    return head;