技術標籤：# 樹leetcode

題目描述

給定一棵二叉樹，想象自己站在它的右側，按照從頂部到底部的順序，返回從右側所能看到的節點值。

示例:

思路

dfs，取每一層最右邊的節點

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
 

class Solution {
    private List<Integer> res = new ArrayList<Integer>();
    public List<Integer> rightSideView(TreeNode root) {
        helpRightSideView(root,0);
        return res;
    }

    public void helpRightSideView(TreeNode root,int deep){
        if(root == null){
            return
 
;
        }
        if(res.size() == deep){
            res.add(root.val);
        }
        deep++;
        helpRightSideView(root.right,deep);
        helpRightSideView(root.left,deep);
    }
}