Tree Traversal Preorder Root Left Right in DSA C++ - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to print the root node's value first in preorder traversal.

DSA C++

void preorder(Node* root) {
    if (root == nullptr) return;
    std::cout << root->[1] << " ";
    preorder(root->left);
    preorder(root->right);
}

Drag options to blanks, or click blank then click option'

Adata

Bval

Cvalue

Dkey

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'val' or 'key' which may not exist in the Node structure.

Trying to print the pointer instead of the value.

The root node's data is accessed by 'data' in this Node structure.

2fill in blank

medium

Complete the code to recursively traverse the left subtree in preorder.

DSA C++

void preorder(Node* root) {
    if (root == nullptr) return;
    std::cout << root->data << " ";
    preorder(root->[1]);
    preorder(root->right);
}

Drag options to blanks, or click blank then click option'

Achild

Bright

Cnext

Dleft

Attempts:

3 left

💡 Hint

Common Mistakes

Calling preorder on 'right' before 'left'.

Using non-existent members like 'child' or 'next'.

In preorder traversal, after the root, we visit the left subtree first, so we call preorder on 'left'.

3fill in blank

hard

Fix the error in the preorder traversal to correctly traverse the right subtree.

DSA C++

void preorder(Node* root) {
    if (root == nullptr) return;
    std::cout << root->data << " ";
    preorder(root->left);
    preorder(root->[1]);
}

Drag options to blanks, or click blank then click option'

Aleft

Bchild

Cright

Dnext

Attempts:

3 left

💡 Hint

Common Mistakes

Calling preorder on 'left' twice.

Using invalid member names like 'child' or 'next'.

After visiting the left subtree, preorder traversal visits the right subtree, so we call preorder on 'right'.

4fill in blank

hard

Fill both blanks to complete the preorder traversal function that prints nodes in Root-Left-Right order.

DSA C++

void preorder(Node* root) {
    if (root == nullptr) return;
    std::cout << root->[1] << " ";
    preorder(root->[2]);
    preorder(root->right);
}

Drag options to blanks, or click blank then click option'

Adata

Bval

Cleft

Dright

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping 'left' and 'right' in traversal order.

Using 'val' instead of 'data' for the node's value.

We print the root's 'data' first, then recursively traverse the 'left' subtree before the right.

5fill in blank

hard

Fill all three blanks to complete the preorder traversal that prints root, left subtree, then right subtree.

DSA C++

void preorder(Node* root) {
    if (root == nullptr) return;
    std::cout << root->[1] << " ";
    preorder(root->[2]);
    preorder(root->[3]);
}

Drag options to blanks, or click blank then click option'

Adata

Bleft

Cright

Dval

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up the order of left and right traversal.

Using 'val' instead of 'data' for the node's value.

Print the root's 'data', then recursively traverse 'left' subtree, then 'right' subtree.