二叉树

给定一个正整数 n,生成结点值为 1 ~ n 的所有二叉查找树: https://leetcode.com/problems/unique-binary-search-trees-ii/ Given an integer n, generate all structurally unique BST’s (binary search trees) that store values 1…n. For example, Given n = 3, your program should return all 5 unique BST’s shown below. 1 3 3 2 1 \ / / / \
二叉树的递归遍历简洁明了,而非递归遍历则相对复杂,三种递归思路有很大区别,还容易忘。如果不用线索二叉树的话,一般要用栈来实现,即便都是用栈实