Write a function named bstGetMin that accepts a pointer to a BinaryTreeNode representing the root of a binary search tree of integers, and returns the smallest integer data value found in the tree.
You may assume that the tree passed is in BST order, meaning that every node N's left subtree is a BST that contains only values less than N's data, and its right subtree is a BST that contains only values greater than N's data.
Your code should take advantage of the ordering of the tree and should not examine any subtrees where there is no possibility for the minimum element value to be present.
If the tree is empty, throw a string exception.
Constraints:
You must implement your function recursively and without using loops.
Do not construct any new BinaryTreeNode objects in solving this problem (though you may create as many BinaryTreeNode* pointer variables as you like).
Do not use any auxiliary data structures to solve this problem (no array, vector, stack, queue, string, etc).
Your function should not modify the tree's state; the state of the tree should remain constant with respect to your function.
Assume that you are using the BinaryTreeNode structure as defined below:
struct BinaryTreeNode {
int data;
BinaryTreeNode* left;
BinaryTreeNode* right;
};
