LeetCode199.cpp

/**
 *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> ans;
        if (root == NULL)
            return ans;
        queue<TreeNode *> q;
        q.push(root);
        while (!q.empty())
        {
            int sz = q.size();
            vector<int> data;
            while (sz)
            {
                TreeNode *node = q.front();
                q.pop();
                data.push_back(node->val);
                if (node->left)
                {
                    q.push(node->left);
                }
                if (node->right)
                {
                    q.push(node->right);
                }
                sz--;
            }
            ans.push_back(data.back());
        }
        return ans;
    }
};