【练习】二叉搜索树经典例题 I

99. 恢复二叉搜索树 https://leetcode.cn/problems/recover-binary-search-tree

669. 修剪二叉搜索树 https://leetcode.cn/problems/trim-a-binary-search-tree

671. 二叉树中第二小的节点 https://leetcode.cn/problems/second-minimum-node-in-a-binary-tree

501. 二叉搜索树中的众数 https://leetcode.cn/problems/find-mode-in-binary-search-tree

530. 二叉搜索树的最小绝对差 https://leetcode.cn/problems/minimum-absolute-difference-in-bst

653. 两数之和 IV - 输入 BST https://leetcode.cn/problems/two-sum-iv-input-is-a-bst

1008. 前序遍历构造二叉搜索树 https://leetcode.cn/problems/construct-binary-search-tree-from-preorder-traversal