题解 | #牛群最小体重差#

• 题目考察的知识点 : 二叉搜索树的性质
• 题目解答方法的文字分析：

1. 我们可以进行中序遍历（即从小到大遍历），并计算相邻节点之间的差值。在计算过程中，我们需要记录最小差值min_diff，初始值为正无穷。每当计算出相邻节点之间的差值时，如果该差值比当前的min_diff要小，则更新min_diff的值

• 本题解析所用的编程语言：Python
• 完整且正确的编程代码

# 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 getMinimumDifference(self, root: TreeNode) -> int:
        stack = []
        cur = root
        pre_val = float("-inf")
        min_diff = float("inf")
        while stack or cur:
            if cur:
                stack.append(cur)
                cur = cur.left
            else:
                node = stack.pop()
                if pre_val != float("-inf"):
                    diff = node.val - pre_val
                    if diff < min_diff:
                        min_diff = diff
                pre_val = node.val
                cur = node.right
        return min_diff