Right Side View of Binary Tree in DSA Typescript - Practice Problems & Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of Right Side View for a Simple Binary Tree

What is the output of the right side view function for the given binary tree?

DSA Typescript

class TreeNode {
  val: number;
  left: TreeNode | null;
  right: TreeNode | null;
  constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
    this.val = val === undefined ? 0 : val;
    this.left = left === undefined ? null : left;
    this.right = right === undefined ? null : right;
  }
}

function rightSideView(root: TreeNode | null): number[] {
  const result: number[] = [];
  if (!root) return result;
  const queue: (TreeNode | null)[] = [root];
  while (queue.length > 0) {
    const size = queue.length;
    for (let i = 0; i < size; i++) {
      const node = queue.shift()!;
      if (node.left) queue.push(node.left);
      if (node.right) queue.push(node.right);
      if (i === size - 1) result.push(node.val);
    }
  }
  return result;
}

// Tree structure:
//      1
//     / \
//    2   3
//     \   \
//      5   4

const root = new TreeNode(1,
  new TreeNode(2, null, new TreeNode(5)),
  new TreeNode(3, null, new TreeNode(4))
);
console.log(rightSideView(root));

A [1, 3, 5]

B [1, 2, 5]

C [1, 3, 4]

D [1, 2, 4]

💡 Hint

Think about which nodes are visible when looking from the right side level by level.

The right side view shows the last node at each level when traversing from left to right.

Level 1: Node 1

Level 2: Node 3 (right child of 1)

Level 3: Node 4 (right child of 3)

🧠 Conceptual

intermediate

Understanding the Right Side View Concept

Which statement best describes the right side view of a binary tree?

A It contains all nodes visible when the tree is viewed from the right side, showing the rightmost node at each level.

B It contains all leaf nodes of the binary tree.

C It contains all nodes in the tree sorted by their values.

D It contains the nodes in the leftmost path from root to leaf.

💡 Hint

Focus on visibility from the right side, not all nodes or sorting.

The right side view includes only the rightmost node at each depth level, as seen from the right side.

🔧 Debug

advanced

Identify the Bug in Right Side View Implementation

What error will this code produce when run, and why?

DSA Typescript

function rightSideView(root: TreeNode | null): number[] {
  const result: number[] = [];
  if (!root) return result;
  const queue: (TreeNode | null)[] = [root];
  while (queue.length > 0) {
    const size = queue.length;
    for (let i = 0; i <= size; i++) {
      const node = queue.shift()!;
      if (node.left) queue.push(node.left);
      if (node.right) queue.push(node.right);
      if (i === size - 1) result.push(node.val);
    }
  }
  return result;
}

A No error: The function runs correctly and returns the right side view.

B Syntax error: Missing semicolon after queue.shift()!

C Wrong output: The function returns an empty array because the loop never runs.

D Runtime error: Cannot read property 'left' of undefined due to accessing queue.shift() when queue is empty.

💡 Hint

Check the loop condition and how many times queue.shift() is called.

The for loop uses i <= size, which runs one extra time than the queue length.

This causes queue.shift() to return undefined, leading to a runtime error when accessing node.left.

❓ Predict Output

advanced

Output of Right Side View for a Left-Skewed Tree

What is the output of the right side view function for this left-skewed binary tree?

DSA Typescript

const root = new TreeNode(10,
  new TreeNode(20,
    new TreeNode(30,
      new TreeNode(40), null), null), null
);
console.log(rightSideView(root));

A [10, 20, 30, 40]

B [10]

C [40]

D [10, 30, 40]

💡 Hint

In a left-skewed tree, the right side view shows all nodes because no right children hide them.

Each level has only one node, so the right side view includes all nodes in the path.

🚀 Application

expert

Number of Nodes in Right Side View for a Complete Binary Tree

Given a complete binary tree of height 4 (root at height 1), how many nodes will the right side view contain?

A 15

B 4

C 7

D 8

💡 Hint

The right side view contains one node per level.

A complete binary tree of height 4 has 4 levels.

The right side view shows exactly one node per level, so 4 nodes total.