题目描述

blablabla

样例

blablabla

算法1

(暴力枚举) $O(n^2)$

blablabla

时间复杂度

参考文献

C++ 代码

class Solution {
public:
    vector<vector<int>> printFromTopToBottom(TreeNode* root) {
        vector<vector<int>> res;
        if(!root) return res;
        queue<TreeNode*> q;
        q.push(root);
        int d = 0;
        while(q.size()){
            int size = q.size();
            vector<int> ans;
            while(size--){
                auto t = q.front();
                q.pop();
                ans.push_back(t->val);
                if(t->left) q.push(t->left);
                if(t->right) q.push(t->right);
            }
            if(d) reverse(ans.begin(),ans.end());
            d = !d;
            res.push_back(ans);
        }
        return res;
    }
};

算法2

(暴力枚举) $O(n^2)$

blablabla

时间复杂度

参考文献

C++ 代码

blablabla