【10月打卡~Leetcode每日一题】530. 二叉搜索树的最小绝对差（难度：简单）

530. 二叉搜索树的最小绝对差

直接深搜，用中序遍历的思想，先找到最左边的节点，一步一步迭代到最右边的节点

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

class Solution:
    def getMinimumDifference(self, root: TreeNode) -> int:
        ans,pre = float('inf'),-1
        
        def dfs(root):
            nonlocal ans,pre
            if not root:
                return

            dfs(root.left)
            
            if pre != -1:
                ans = min(ans,root.val-pre)
            
            pre = root.val
            dfs(root.right)

        dfs(root)
        return ans

时间复杂度O(n)