Return the minimum absolute difference between values of any two nodes in the BST.
Examples
Input:[4,2,6,1,3]
Output:1
Input:[1,0,48,null,null,12,49]
Output:1
Hints
Utilize the property of BST that an inorder traversal yields nodes in ascending order.
During traversal, compare the current node's value with the previous node's value to compute the absolute difference and keep track of the minimum difference encountered.
Optimize space by avoiding storing the entire traversal; instead, maintain only the previous node's value and update the minimum difference on the fly.