无法理解此Python代码中的tree.value

Question

这是Python中leet代码问题270（在BST中查找最接近的值）的答案。我无法理解这段代码中的tree.value是什么以及如何工作的

def findClosestValueInBst(tree, target):
    return findClosestValueInBstHelper(tree, target, closest)

def findClosestValueInBstHelper(tree, target, closest):
    if tree is None:
       return Closest
    if abs(target - closest) > abs(target - tree.value):
       closest = tree.value
    if target < tree.value:
       return findClosestValueInBstHelper(tree.left, target, closest)
    elif target > tree.vlaue:
       return findClosestValueInBstHelper(tree.right, target, closest)
    else:
       return closest

Answer 1

有一个由LeetCode定义的TreeNode类，您不必将其添加到解决方案中：

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None

这将通过：

# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def closestValue(self, root, target):
        a_value = root.val
        child = root.left if target < a_value else root.right
        if not child: 
            return a_value
        b_value = self.closestValue(child, target)
        return min((b_value, a_value), key=lambda x: abs(target - x))

而且，没有tree.value，我想应该是tree.val

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参考资料

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