https://leetcode-cn.com/problems/maximum-depth-of-binary-tree/
1. 采用递归法。
https://leetcode-cn.com/problems/minimum-depth-of-binary-tree/
1. 采用递归法。
https://leetcode-cn.com/problems/binary-tree-level-order-traversal/
1. 采用bfs的方法.
2. 采用dft的方法.
https://leetcode-cn.com/problems/lowest-common-ancestor-of-a-binary-tree/
采用递归的方法
https://leetcode-cn.com/problems/lowest-common-ancestor-of-a-binary-search-tree/
采用递归的方法