如何在python中将平衡二叉树的结果保存为数组

Question

下面的 Python 程序将给定的数组元素转换为高度平衡的二叉搜索树 (BST)，并打印构造的 BST 的遍历。我想知道如何将结果保存为数组。

class TreeNode(object):
    def __init__(self, x):
        self.val = x
        self.left = None
        self.right = None

def array_to_bst(array_nums):
    if not array_nums:
        return None
    mid_num = len(array_nums)//2
    node = TreeNode(array_nums[mid_num])
    node.left = array_to_bst(array_nums[:mid_num])
    node.right = array_to_bst(array_nums[mid_num+1:])
    return node

def preOrder(node): 
    if not node: 
        return      
    print(node.val)
    preOrder(node.left) 
    preOrder(node.right)   

array_nums = [1,2,3,4,5,6,7]

print("Original array:")
print(array_nums)
result = array_to_bst(array_nums)
print("\nArray to a height balanced BST:")
print(preOrder(result))

Answer 1

只需将您的 preOrder(node) 函数更改为：

def preOrder(node): 
    if node is None: 
        return []
    print(node.val)
    res = [node.val]
    res += preOrder(node.left) 
    res += preOrder(node.right)
    return res