镜像二进制搜索树 [英] Mirror Binary Search Tree

问题描述

这是给出二进制搜索树根的代码，用于创建其镜像.

This is a code that given a root of the binary search tree, is to create its mirror.

def mirror(root):
    if root is None:
        pass
    else:
        mirror(root.left)
        mirror(root.right)
        temp = root.left
        root.left = root.right
        root.right = temp

首先，这段代码正确吗?这里的递归是否应该首先到达树的叶子，然后在展开时切换引用?

Firstly, is this code right and also is the recursion here supposed to first get to the leaves of the tree first and then switch the references when unwinding?

推荐答案

是正确的，但不是Pythonic.

It's right, but not very Pythonic.

更好地写作

def mirror(root):
    if root is None:
        return
    mirror(root.left)
    mirror(root.right)
    root.left, root.right = root.right, root.left

对于此问题，您可以按任何顺序进行递归(在父级之前或之后将叶子反向).

For this problem, you could recurse in either order (either reversing the leaves before the parents or after).

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