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

Practice - 5 Tasks

1fill in blank

easy

Complete the code to call the postorder traversal function recursively on the left child.

DSA C++

void postorder(Node* root) {
    if (root == nullptr) return;
    postorder(root->[1]);
    // Continue traversal
}

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

Aright

Bchild

Cparent

Dleft

Attempts:

3 left

💡 Hint

Common Mistakes

Calling postorder on root->right first.

Calling postorder on root->parent which does not exist.

Using an incorrect pointer name.

In postorder traversal, we first visit the left subtree, so we call postorder on root->left.

2fill in blank

medium

Complete the code to call the postorder traversal function recursively on the right child.

DSA C++

void postorder(Node* root) {
    if (root == nullptr) return;
    postorder(root->left);
    postorder(root->[1]);
    // Continue traversal
}

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

Aright

Bparent

Cchild

Droot

Attempts:

3 left

💡 Hint

Common Mistakes

Calling postorder on root->left again.

Using root->parent which is not part of traversal.

Using an invalid pointer name.

In postorder traversal, after visiting the left subtree, we visit the right subtree by calling postorder on root->right.

3fill in blank

hard

Fix the error in the code to print the root node's value after traversing left and right subtrees.

DSA C++

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

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

Aright

Bleft

Cdata

Dvalue

Attempts:

3 left

💡 Hint

Common Mistakes

Printing root->left or root->right which are pointers.

Using root->value which may not exist.

Forgetting to print the root node.

The root node's data is stored in the 'data' member, so we print root->data after traversing children.

4fill in blank

hard

Fill both blanks to complete the postorder traversal function that returns a vector of node values.

DSA C++

void postorder(Node* root, std::vector<int>& result) {
    if (root == nullptr) return;
    postorder(root->[1], result);
    postorder(root->[2], result);
    result.push_back(root->data);
}

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

Aleft

Bright

Cparent

Dchild

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping left and right child pointers.

Using 'parent' or 'child' which are invalid pointers.

Forgetting to pass 'result' vector.

Postorder visits left child first, then right child, so blanks are 'left' and 'right'.

5fill in blank

hard

Fill all three blanks to create a postorder traversal that returns a map from node data to its depth in the tree.

DSA C++

void postorder(Node* root, std::map<int, int>& depthMap, int depth) {
    if (root == nullptr) return;
    postorder(root->[1], depthMap, depth + 1);
    postorder(root->[2], depthMap, depth + 1);
    depthMap[root->[3]] = depth;
}

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

Aleft

Bright

Cdata

Dvalue

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'value' instead of 'data' for node value.

Swapping left and right pointers.

Not incrementing depth correctly.

Traverse left and right children first, then map root->data to current depth.