530. Minimum Absolute Difference in BST

Problem Link

Description

---

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/

Solution

---

Python3

# 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 getMinimumDifference(self, root: Optional[TreeNode]) -> int:
        M = 10 ** 5 + 1
        res = prev = M
 
        def go(node):
            nonlocal res, prev
            
            if node.left:
                go(node.left)
            
            res = min(res, abs(node.val - prev))
            prev = node.val
 
            if node.right:
                go(node.right)
        
        go(root)
        return res