代码分析

实际上就是二叉树的遍历的变形，将高度考虑进入即可

代码实现

import java.util.ArrayList;
import java.util.List;
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    public List<Integer> rightSideView(TreeNode root) {
        ArrayList<Integer> res=new ArrayList();
        f(root,res,0);
        return res;
   }
   public void f(TreeNode root,ArrayList<Integer> res,int lindex)
   {
       if(root==null) return ;
       if(res.size()<=lindex)
       {
           res.add(root.val);
       }else
       {
           res.set(lindex,root.val);
       }
       f(root.left,res,lindex+1);
       f(root.right,res,lindex+1);
   }
}