void BinarySearchTree<T>::traverseInorder(Node<T> *curNode) {
if(curNode) {
traverseInorder(curNode->getLeft());
std::cout << " " << curNode->getElement();
traverseInorder(curNode->getRight());
}
}
// in order traversal of a tree.
void traverseInorder(BTreeNode *head, vector<int> &vals) {
if(NULL == head) return ;
traverseInorder(head->left, vals);
vals.push_back(head->val);
traverseInorder(head->right, vals);
}
void BinarySearchTree<T>::traverseInorder() {
std::cout << "Tree Inorder traversal: ";
if(!root)
std::cout << "(nil)";
traverseInorder(root);
std::cout << "\n";
}
////////////////////////////////////////////////////////////////
// test if a tree is BST.
////////////////////////////////////////////////////////////////
// the property of a binary search tree is that its left subtree
// is smaller than its root and right subtree is bigger than root.
////////////////////////////////////////////////////////////////
// suppose we use the same node as the previous one.
bool checkBST(BTreeNode *head) {
if(NULL == head) return true;
// traverse the tree inorder.
vector<int> inorderVals;
traverseInorder(head, inorderVals);
int len = inorderVals.size();
for(int i = 0; i < len - 1; ++i) {
if(inorderVals[i] > inorderVals[i+1]) return false;
}
return true;
}
