递归实战题目
https://leetcode-cn.com/problems/climbing-stairs/
https://leetcode-cn.com/problems/generate-parentheses/
https://leetcode-cn.com/problems/invert-binary-tree/description/
https://leetcode-cn.com/problems/validate-binary-search-tree
https://leetcode-cn.com/problems/maximum-depth-of-binary-tree
https://leetcode-cn.com/problems/minimum-depth-of-binary-tree
https://leetcode-cn.com/problems/serialize-and-deserialize-binary-tree/
课后作业
https://leetcode-cn.com/problems/lowest-common-ancestor-of-a-binary-tree/
https://leetcode-cn.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal
https://leetcode-cn.com/problems/combinations/
https://leetcode-cn.com/problems/permutations/
https://leetcode-cn.com/problems/permutations-ii/
分治与回溯预习题目
https://leetcode-cn.com/problems/powx-n/
https://leetcode-cn.com/problems/subsets/
实战题目
https://leetcode-cn.com/problems/majority-element/description/ （简单、但是高频）
https://leetcode-cn.com/problems/letter-combinations-of-a-phone-number/
https://leetcode-cn.com/problems/n-queens/
本周作业 中等：
https://leetcode-cn.com/problems/lowest-common-ancestor-of-a-binary-tree/
https://leetcode-cn.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal/
https://leetcode-cn.com/problems/combinations/
https://leetcode-cn.com/problems/permutations/
https://leetcode-cn.com/problems/permutations-ii/
下周预习
预习题目：
二叉树的层次遍历
分发饼干
买卖股票的最佳时机 II
跳跃游戏
x 的平方根
有效的完全平方数