/*     * 272. Closest Binary Search Tree Value II     * 2016-7-21 by Mingyang     * 一次过，dfs和list     */      public List
     
       closestKValues(TreeNode root, double target, int k) {            List
      
        list=new ArrayList
       
        ();            if(root==null)              return list;            Stack
        
          stack=new Stack
         
          ();            TreeNode p=root;            while(!stack.isEmpty()||p!=null){                if(p!=null){                    stack.push(p);                    p=p.left;                }else{                    TreeNode q=stack.pop();                    if(list.size()
          
           Math.abs(q.val-target)){ list.remove(0); list.add(q.val); }else{ return list; } } p=q.right; } } return list; }