Top View of Binary Tree in DSA C++ - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a struct for a binary tree node.

DSA C++

struct Node {
    int data;
    Node* left;
    Node* [1];
    Node(int val) : data(val), left(nullptr), right(nullptr) {}
};

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

Achild

Bparent

Cnext

Dright

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'parent' instead of 'right' for the right child pointer.

Using 'next' which is common in linked lists but not binary trees.

The right child pointer in a binary tree node is commonly named 'right'.

2fill in blank

medium

Complete the code to insert the root node into the queue for level order traversal.

DSA C++

std::queue<std::pair<Node*, int>> q;
q.push([1], 0});

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Aroot

Broot->data

Cnullptr

Dnew Node(0)

Attempts:

3 left

💡 Hint

Common Mistakes

Pushing root->data instead of root pointer.

Pushing nullptr which causes runtime errors.

We push the root node pointer itself, not its data, into the queue for traversal.

3fill in blank

hard

Fix the error in the condition to check if a horizontal distance is not yet in the map.

DSA C++

if (topViewMap.find([1]) == topViewMap.end()) {
    topViewMap[hd] = node->data;
}

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Ahd

Bnode->data

Cnode

DtopViewMap

Attempts:

3 left

💡 Hint

Common Mistakes

Checking for node->data instead of hd in the map.

Using the map itself as a key.

We check if the horizontal distance 'hd' is in the map, not the node data.

4fill in blank

hard

Fill both blanks to correctly update the queue with left and right children and their horizontal distances.

DSA C++

if (node->left) q.push({node->left, hd [1] 1});
if (node->right) q.push({node->right, hd [2] 1});

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A-

B+

C*

D/

Attempts:

3 left

💡 Hint

Common Mistakes

Adding 1 to left child hd or subtracting 1 from right child hd.

Using multiplication or division instead of addition/subtraction.

Left child horizontal distance is hd - 1; right child is hd + 1.

5fill in blank

hard

Fill all three blanks to create a map from horizontal distance to node data, and print the top view in order.

DSA C++

std::map<int, int> topViewMap;
// After filling topViewMap
for (auto [1] : topViewMap) {
    std::cout << [2] << ' ';
}
std::cout << std::endl;

// Function signature
std::vector<int> topView(Node* [3]) { /* ... */ }

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

Apair

Bsecond

Croot

Dfirst

Attempts:

3 left

💡 Hint

Common Mistakes

Printing the key (first) instead of the value (second).

Using wrong variable names in the loop.

Wrong function parameter name.

We iterate over map pairs, print the second (node data), and the function takes root node pointer.