[leetcode] 783. Minimum Distance Between BST Nodes

Given the root of a Binary Search Tree (BST), return the minimum 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, 100].
• 0 <= Node.val <= 105

 

# Definition for a binary tree node.
# class TreeNode(object):
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution(object):
    import sys
    prev = -sys.maxsize 
    result = sys.maxsize

    def minDiffInBST(self, root):
        """
        :type root: TreeNode
        :rtype: int
        """
        if root.left:
            self.minDiffInBST(root.left)

        self.result = min(self.result, root.val - self.prev)
        self.prev = root.val 

        if root.right:
            self.minDiffInBST(root.right)

        return self.result