程式語言 - LeetCode - C++ - 199. Binary Tree Right Side View

參考資訊：
https://www.cnblogs.com/grandyang/p/4392254.html

題目：


解答：

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    vector<int> rightSideView(TreeNode* root) {
        vector<int> r;
        queue<TreeNode*> q;

        if (!root) {
            return r;
        }

        q.push(root);
        while (q.size() > 0) {
            r.push_back(q.back()->val);

            int len = q.size();
            for (int i = 0; i < len; i++) {
                TreeNode *t = q.front();

                q.pop();
                if (t->left) {
                    q.push(t->left);
                }

                if (t->right) {
                    q.push(t->right);
                }
            }
        }

        return r;
    }
};