[LeetCode][Medium] 199. Binary Tree Right Side View

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

題目說明:

給定一個 Binary Tree，請由 Top 至 Bottom 出每一層中最右邊 Node 的值。

解題說明:

題目很清楚，就是一題 Level Order Traversal 的題目，所以直接用 queue 處理即可。

程式碼

class Solution {
public:
    vector<int> rightSideView(TreeNode* root) {
        vector<int> ans;
        queue<TreeNode*> q;
        
        if (root) q.push(root);
        while (q.size() > 0) {
            TreeNode* rightNode = NULL;
            for (int i = 0, size = q.size(); i < size; i++, q.pop()) {
                rightNode = q.front();
                if (rightNode->left) q.push(rightNode->left);
                if (rightNode->right) q.push(rightNode->right);
            }
            if (rightNode) ans.push_back(rightNode->val);
        }
        return ans;
    }
};

結果

Runtime: 0 ms, faster than 100.00% of C++ online submissions for Binary Tree Right Side View.

Memory Usage: 11.8 MB, less than 29.31% of C++ online submissions for Binary Tree Right Side View.