Right Side View of Binary Tree in DSA C - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the "Right Side View" of a binary tree?

The right side view of a binary tree is the set of nodes visible when the tree is seen from the right side. It includes the rightmost node at each level of the tree.

beginner

Which traversal method is commonly used to find the right side view of a binary tree?

Level order traversal (Breadth-First Search) is commonly used, visiting nodes level by level and recording the last node at each level.

intermediate

In the right side view algorithm, why do we record the last node at each level?

Because the last node visited at each level during a left-to-right level order traversal is the rightmost node visible from the right side.

beginner

What data structure is typically used to implement level order traversal for the right side view?

A queue is used to hold nodes of the current level while traversing the tree level by level.

intermediate

How does the right side view differ from the left side view of a binary tree?

The right side view shows the rightmost nodes at each level, while the left side view shows the leftmost nodes at each level when viewed from the respective sides.

What is the main goal when finding the right side view of a binary tree?

A To find the leftmost node at each level

B To find the rightmost node at each level

C To find all leaf nodes

D To find the root node only

The right side view consists of the rightmost nodes visible at each level of the tree.

Which data structure helps to perform level order traversal efficiently?

A Queue

B Stack

C Array

D Linked List

A queue is used to process nodes level by level in breadth-first search.

During level order traversal, which node do we record for the right side view at each level?

A The last node at the level

B The first node at the level

C The middle node at the level

D All nodes at the level

The last node visited at each level is the rightmost node visible from the right side.

If a binary tree has only left children, what will the right side view look like?

A It will show only leaf nodes

B It will show only the root node

C It will show all nodes since they are all rightmost at their levels

D It will be empty

If nodes only have left children, each node is the rightmost at its level, so all nodes appear in the right side view.

What is the time complexity of finding the right side view using level order traversal?

A O(log n)

B O(n log n)

C O(n^2)

D O(n)

Each node is visited once, so the time complexity is linear, O(n), where n is the number of nodes.

Explain how to find the right side view of a binary tree using level order traversal.

Think about visiting nodes one level at a time and picking the rightmost node.

Describe the difference between the right side view and left side view of a binary tree.

Consider which nodes are visible from each side.

Practice

1. What does the "Right Side View" of a binary tree represent?

easy

A. All leaf nodes of the tree

B. Nodes visible when the tree is viewed from the left side

C. Nodes visible when the tree is viewed from the right side

D. Nodes at the deepest level only

Solution

1. Step 1: Understand the view perspective

   The right side view shows nodes visible when looking at the tree from the right side.

2. Step 2: Identify visible nodes

   Only the rightmost node at each level is visible from the right side.

3. Final Answer:

   Nodes visible when the tree is viewed from the right side -> Option C

4. Quick Check:

   Right side view = rightmost nodes [OK]

Hint: Right side view shows rightmost nodes at each level [OK]

Common Mistakes:

• Confusing right side view with left side view
• Thinking it shows all leaf nodes
• Assuming it shows only deepest nodes

2. Which of the following C code snippets correctly declares a binary tree node structure for use in right side view algorithms?

easy

A. typedef struct Node { int val; struct Node* left; struct Node* right; } Node;

B. struct Node { int val; Node* left; Node* right; }; typedef Node;

C. typedef struct { int val; struct Node* left; struct Node* right; } Node;

D. struct Node { int val; struct Node left; struct Node right; }; typedef struct Node Node;

Solution

1. Step 1: Check struct declaration syntax

   typedef struct Node { int val; struct Node* left; struct Node* right; } Node; correctly declares a struct with pointers to left and right child nodes.

2. Step 2: Verify typedef usage

   typedef struct Node { int val; struct Node* left; struct Node* right; } Node; uses typedef properly to alias struct Node as Node.

3. Final Answer:

   typedef struct Node { int val; struct Node* left; struct Node* right; } Node; -> Option A

4. Quick Check:

   Correct struct with pointers and typedef [OK]

Hint: Use struct with pointers and typedef for node [OK]

Common Mistakes:

• Missing struct keyword before pointer types
• Using struct members as values instead of pointers
• Incorrect typedef syntax

3. Given the following binary tree and code snippet, what is the output of the right side view function?

    1
   / \
  2   3
   \   \
    5   4

// Function call: rightSideView(root);

medium

A. [1, 2, 4]

B. [1, 2, 5]

C. [1, 3, 5]

D. [1, 3, 4]

Solution

1. Step 1: Identify rightmost nodes at each level

   Level 0: Node 1; Level 1: Node 3; Level 2: Node 4.

2. Step 2: Collect nodes in order

   The right side view list is [1, 3, 4].

3. Final Answer:

   [1, 3, 4] -> Option D

4. Quick Check:

   Rightmost nodes per level = [1, 3, 4] [OK]

Hint: Pick rightmost node at each tree level [OK]

Common Mistakes:

• Choosing left child nodes instead of rightmost
• Including nodes not visible from right side
• Confusing node values at levels

4. The following C function attempts to print the right side view of a binary tree but has a bug. What is the error?

void rightSideViewHelper(Node* root, int level, int* maxLevel) {
    if (!root) return;
    if (level > *maxLevel) {
        printf("%d ", root->val);
        *maxLevel = level;
    }
    rightSideViewHelper(root->left, level + 1, maxLevel);
    rightSideViewHelper(root->right, level + 1, maxLevel);
}

medium

A. The function visits left child before right, so right side nodes may be missed

B. The maxLevel pointer is not updated correctly

C. The base case does not check for null root

D. The printf statement is missing a newline character

Solution

1. Step 1: Analyze traversal order

   The function visits left child before right child, so rightmost nodes may be overshadowed by left nodes.

2. Step 2: Understand impact on right side view

   Right side view requires visiting right child first to capture rightmost nodes at each level.

3. Final Answer:

   The function visits left child before right, so right side nodes may be missed -> Option A

4. Quick Check:

   Visit right child first for correct right side view [OK]

Hint: Traverse right child before left child [OK]

Common Mistakes:

• Visiting left child before right child
• Not updating maxLevel properly
• Ignoring base case for null nodes

5. You want to modify a function that returns the right side view of a binary tree to also return the left side view in a single traversal. Which approach is best?

hard

A. Perform two separate traversals: one right-first for right view, one left-first for left view

B. Use a single traversal visiting both children and track first node at each level for left and last for right

C. Use a single traversal visiting right child first, store rightmost nodes, then visit left child for leftmost nodes

D. Traverse only left child and assume it covers both views

Solution

1. Step 1: Understand views require different nodes

   Right view needs rightmost nodes; left view needs leftmost nodes at each level.

2. Step 2: Use single traversal with tracking

   Track first node seen at each level for left view and last node for right view during one traversal.

3. Step 3: Avoid separate traversals for efficiency

   This approach reduces time by combining both views in one pass.

4. Final Answer:

   Use a single traversal visiting both children and track first node at each level for left and last for right -> Option B

5. Quick Check:

   Track first and last nodes per level in one traversal [OK]

Hint: Track first and last nodes per level in one traversal [OK]

Common Mistakes:

• Doing two full traversals unnecessarily
• Visiting only one child and missing nodes
• Not tracking nodes per level properly