check binary search tree algo

BinarySearchTree/isBST.cpp

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+/**
+ * check whether the given binary tree is Binary Search Tree or not.
+*/
+#include <iostream>
+#include <limits>
+#include "BST/BST.hpp"
+
+/* Function Declarations */
+bool isBST(Node* root);
+bool isBSTUtil(Node* root, int minValue, int maxValue);
+
+/* Main Operational Function */
+int main()
+{
+    BST tree1;
+    int original[] = { 9, 5, 3, 10, 6, 1, 7, 4 };
+    for (int i : original)
+        tree1.insert(i);
+    std::cout << "is tree1 bst? " << isBST(tree1.getRoot()) << "\n";
+
+    BST tree2;
+    tree2.insert(5);
+    Node* root = tree2.getRoot();
+    root->right = new Node(7);
+    root->left = new Node(3);
+    root->left->left = new Node(1);
+    root->left->right = new Node(4);
+    root->right->right = new Node(6);
+    std::cout << "is tree2 bst? " << isBST(tree2.getRoot()) << "\n";
+
+    return 0;
+}
+
+/**
+ * checks if binary tree is BST
+ * @param root root of binary (sub)tree
+ * @return true if binary (sub)tree is BST, else false
+*/
+bool isBST(Node* root)
+{
+    return isBSTUtil(root, INT_MIN, INT_MAX);
+}
+
+/**
+ * binary search tree check utility function
+ * @param root root of binary (sub)tree
+ * @param minValue tree nodes should be greater than minValue
+ * @param maxValue tree nodes should be less than maxValue
+ * @return true if binary (sub)tree is BST, else false
+*/
+bool isBSTUtil(Node* root, int minValue, int maxValue)
+{
+    if (root == nullptr)
+        return true;
+
+    if (root->data >= minValue && root->data < maxValue
+        && isBSTUtil(root->left, minValue, root->data)
+        && isBSTUtil(root->right, root->data, maxValue))
+        return true;
+    return false;
+}