题目描述

题目链接：二叉树的层序遍历

根据上一篇文章的模板可以直接写代码，需要改变的就是将N叉树的child改为二叉树的left和right。

代码

class Solution {
public:
    vector<vector<int>> levelOrder(TreeNode* root) {
        vector<vector<int>> res;
        queue<TreeNode*> q;

        if (root == nullptr)
            return res;
        
        q.push(root);

        while(q.size())
        {
            vector<int> tmp;
            int sz = q.size();

            for (int i = 0; i < sz; ++ i)
            {
                TreeNode* t = q.front();
                q.pop();
                tmp.push_back(t->val);

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

            res.push_back(tmp);
        }

        return res;
    }
};