剑指Offer：二叉搜索树与双向链表（Python语言实现）

输入一棵二叉搜索树，将该二叉搜索树转换成一个排序的双向链表。

把树分为3部分：根节点、左子树和右子树，然后把左子树中最大的节点、根节点、右子树中最小的节点链接起来。至于如何把左子树和右子树内部的节点链接成链表，那和原来的问题的实质是一样的，可以递归解决。

class Solution:
    def convert_binary_search_tree(self, root):
        if not root:
            return root
        if not root.left and not root.right:
            return root

        self.convert_binary_search_tree(root.left)
        pre = root.left
        if pre:
            while pre.right:
                pre = pre.right
            root.left, pre.right = pre, root

        self.convert_binary_search_tree(root.right)
        back = root.right
        if back:
            while back.left:
                back = back.left
            root.right, back.left = back, root

        while root.left:
            root = root.left

        return root


st = Solution()
bt = TreeNode(10)
bt.left = TreeNode(6)
bt.right = TreeNode(14)
bt.left.left = TreeNode(4)
bt.left.right = TreeNode(8)
bt.right.left = TreeNode(12)
bt.right.right = TreeNode(16)

head = st.convert_binary_search_tree(bt)
while head:
    print(head.val)
    head = head.right

（最近更新：2019年07月24日）