图解LeetCode第 199 号问题：二叉树的右视图

 1class Solution {
 2public:
 3    vector<int> rightSideView(TreeNode *root) {
 4        vector<int> res;
 5        if (!root) return res;
 6        queue<TreeNode*> q;
 7        q.push(root);
 8        while (!q.empty()) {
 9            res.push_back(q.back()->val);
10            int size = q.size();
11            for (int i = 0; i < size; ++i) {
12                TreeNode *node = q.front();
13                q.pop();
14                if (node->left) q.push(node->left);
15                if (node->right) q.push(node->right);
16            }
17        }
18        return res;
19    }
20};