[leetcode] Binary Tree Right Side View

From : https://leetcode.com/problems/binary-tree-right-side-view/

Given a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered from top to bottom.

For example:
Given the following binary tree,

   1            <--- /   \2     3         <--- \     \  5     4       <---

You should return [1, 3, 4].

/** * Definition for a binary tree node. * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public:    vector<int> rightSideView(TreeNode* root) {        vector<int> res;        if(!root) return res;        queue<TreeNode> box;        box.push(*root);        int up=1, cur=0;        while(up) {            TreeNode node(0);            while(up) {                up--;                node = box.front();box.pop();if(node.left) {box.push(*node.left); cur++;}                if(node.right) {box.push(*node.right); cur++;}            }            res.push_back(node.val);            up = cur;            cur = 0;        }        return res;    }};