给定一棵二叉树，想象自己站在它的右侧，按照从顶部到底部的顺序，返回从右侧所能看到的节点值。
示例:
输入: [1,2,3,null,5,null,4] 输出: [1, 3, 4] 解释: 1 <--- / \ 2 3 <--- \ \ 5 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> vecRes; if(NULL == root) return vecRes; list<TreeNode *> listRepo; listRepo.push_back(root); while(!listRepo.empty()) { int count = listRepo.size(); vecRes.push_back(listRepo.front()->val); while(count--) { TreeNode *pNode = listRepo.front(); listRepo.pop_front(); if(pNode->right) listRepo.push_back(pNode->right); if(pNode->left) listRepo.push_back(pNode->left); } } return vecRes; } };采用层序遍历的方式，先访问右节点，再访问左节点
