中序遍历后,求数组间差值

# class TreeNode:
#     def __init__(self, x):
#         self.val = x
#         self.left = None
#         self.right = None
#
# 代码中的类名、方法名、参数名已经指定,请勿修改,直接返回方法规定的值即可
#
# 
# @param root TreeNode类 
# @return int整型
#
class Solution:
    def minDifference(self , root: TreeNode) -> int:
        # write code here
        order_list = []
        def in_order(root):
            nonlocal order_list
            if not root:
                return
            in_order(root.left)
            order_list.append(root.val)
            in_order(root.right)
        in_order(root)
        diff = float("inf")
        for i in range(1, len(order_list)):
            diff = min(diff, order_list[i] - order_list[i - 1])
        return diff