Inorder traversal visits nodes in the order: left subtree → current node → right subtree. For a BST, inorder traversal produces values in sorted ascending order. It is implemented simply with recursion or with an explicit stack for the iterative version.
void inorder(Node* root, vector<int>& result) {
if (!root) return;
inorder(root->left, result);
result.push_back(root->val);
inorder(root->right, result);
}Inorder traversal follows the pattern: recurse left, visit node, recurse right. For a BST this produces values in ascending sorted order, which is why it is the most commonly used tree traversal.
Inorder traversal is used to: print BST values sorted, validate a BST (check if inorder output is strictly increasing), and convert BST to sorted array.
Use an explicit stack: push nodes going left until null, then pop, process, and go right. This avoids recursion stack overflow for very deep trees.
Quiz coming soon for this algorithm.