Minimum absolute difference in bst

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def __init__(self):
        self.prev = None
        self.is_valid = True
        self.res = math.inf
    def inorder(self, root):
        if not root or not self.is_valid:
            return None
        self.inorder(root.left)
        if self.prev is not None:
            self.res = min(root.val - self.prev, self.res)
        self.prev = root.val
        self.inorder(root.right)

    def getMinimumDifference(self, root: Optional[TreeNode]) -> int:
        self.inorder(root)
        return self.res

Minimum Absolute Difference in BST

Difficulty: Easy

Given the root of a Binary Search Tree (BST), return the minimum absolute difference between the values of any two different nodes in the tree.

 

Example 1:

Input: root = [4,2,6,1,3]
Output: 1

Example 2:

Input: root = [1,0,48,null,null,12,49]
Output: 1

 

Constraints:

  • The number of nodes in the tree is in the range [2, 104].
  • 0 <= Node.val <= 105

 

Note: This question is the same as 783: https://leetcode.com/problems/minimum-distance-between-bst-nodes/