Data Structures & Algorithms for Competitive Exam Prep

Data Structures & Algorithms

Q. Given a linked list, how can you determine if it contains a cycle?

A. Using a hash table
B. Using two pointers
C. Using recursion
D. All of the above

Solution

You can use a hash table to track visited nodes, two pointers to detect cycles, or recursion to check for cycles, making all methods valid.

Correct Answer: D — All of the above

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Q. How are arrays utilized in image processing applications?

A. To store pixel data
B. To manage user input
C. To implement sorting algorithms
D. To create linked lists

Solution

Arrays are used to store pixel data in image processing applications, where each element represents a pixel's color value.

Correct Answer: A — To store pixel data

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Q. How are trees commonly used in real-world applications?

A. To represent hierarchical data like file systems
B. To store data in a linear fashion
C. To implement a stack
D. To perform linear searches

Solution

Trees are commonly used to represent hierarchical data, such as file systems, where each node can have multiple children.

Correct Answer: A — To represent hierarchical data like file systems

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Q. How are trees utilized in real-world applications?

A. For hierarchical data representation
B. For linear data storage
C. For implementing stacks
D. For managing memory allocation

Solution

Trees are used for hierarchical data representation, such as file systems and organizational structures.

Correct Answer: A — For hierarchical data representation

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Q. How can binary search be modified to find the first occurrence of a target value in a sorted array with duplicates?

A. Use a linear search
B. Modify the mid-point logic
C. Use a stack
D. Use a queue

Solution

By modifying the mid-point logic to continue searching in the left half even after finding the target.

Correct Answer: B — Modify the mid-point logic

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Q. How can binary trees be applied in artificial intelligence?

A. For decision-making processes
B. For sorting data
C. For searching algorithms
D. For data compression

Solution

Binary trees can be used in AI for decision trees, which help in making decisions based on various conditions.

Correct Answer: A — For decision-making processes

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Q. How can binary trees be applied in the field of artificial intelligence?

A. For decision-making processes
B. For data encryption
C. For network security
D. For image rendering

Solution

Binary trees can represent decision trees in AI, where each node represents a decision point leading to different outcomes.

Correct Answer: A — For decision-making processes

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Q. How can linked lists be used in implementing undo functionality in applications?

A. By storing previous states in a stack
B. By maintaining a history of actions in a linked list
C. By using arrays to store actions
D. By creating a binary tree of actions

Solution

Linked lists can maintain a history of actions, allowing for easy traversal back to previous states for undo functionality.

Correct Answer: B — By maintaining a history of actions in a linked list

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Q. How can stacks be used to check for balanced parentheses in an expression?

A. By counting the number of parentheses
B. By using a queue to store parentheses
C. By pushing opening parentheses onto the stack and popping for closing ones
D. By sorting the parentheses

Solution

Stacks can be used to check for balanced parentheses by pushing opening ones and popping when a closing one is encountered.

Correct Answer: C — By pushing opening parentheses onto the stack and popping for closing ones

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Q. How do AVL trees ensure balance after insertion?

A. By performing a single rotation
B. By performing multiple rotations
C. By ignoring balance factors
D. By using a hash table

Solution

AVL trees ensure balance after insertion by performing multiple rotations as needed based on the balance factors of the nodes.

Correct Answer: B — By performing multiple rotations

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Q. How do AVL trees handle insertion that causes imbalance?

A. By performing a single rotation
B. By performing a double rotation
C. By ignoring the new node
D. By deleting the node causing imbalance

Solution

When an insertion causes an imbalance in an AVL tree, it is corrected by performing either a single or a double rotation, depending on the case.

Correct Answer: B — By performing a double rotation

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Q. How do AVL trees maintain balance after insertion?

A. By performing rotations.
B. By deleting nodes.
C. By increasing the height of the tree.
D. By changing node colors.

Solution

AVL trees maintain balance by performing rotations (single or double) after insertions that cause imbalance.

Correct Answer: A — By performing rotations.

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Q. How do stacks help in the execution of function calls in programming languages?

A. They store global variables.
B. They manage the order of execution.
C. They keep track of local variables and return addresses.
D. They optimize memory usage.

Solution

Stacks keep track of local variables and return addresses during function calls, enabling proper execution flow.

Correct Answer: C — They keep track of local variables and return addresses.

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Q. How do you determine the height of a binary tree?

A. Count the number of nodes
B. Count the number of edges
C. Maximum depth of any node
D. Minimum depth of any node

Solution

The height of a binary tree is defined as the maximum depth of any node, which is the longest path from the root to a leaf.

Correct Answer: C — Maximum depth of any node

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Q. How do you find the height of a binary tree?

A. Count the number of nodes
B. Count the number of edges
C. Use level order traversal
D. Use in-order traversal

Solution

The height of a binary tree is defined as the number of edges on the longest path from the root to a leaf node.

Correct Answer: B — Count the number of edges

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Q. How do you perform a left rotation in an AVL tree?

A. By moving the right child up and the current node down.
B. By moving the left child up and the current node down.
C. By swapping the current node with its parent.
D. By reversing the tree structure.

Solution

A left rotation involves moving the right child of a node up to take its place, while the current node becomes the left child of the new root.

Correct Answer: A — By moving the right child up and the current node down.

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Q. How do you perform a left rotation on a node in an AVL tree?

A. Make the right child the new root of the subtree
B. Make the left child the new root of the subtree
C. Swap the node with its parent
D. No rotation is needed

Solution

A left rotation involves making the right child the new root of the subtree and adjusting the left child accordingly.

Correct Answer: A — Make the right child the new root of the subtree

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Q. How does a Red-Black tree ensure balance after deletion?

A. By performing rotations and recoloring.
B. By deleting the node and not balancing.
C. By merging nodes.
D. By increasing the height of the tree.

Solution

After deletion in a Red-Black tree, balance is restored through a combination of rotations and recoloring.

Correct Answer: A — By performing rotations and recoloring.

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Q. How does a Red-Black Tree ensure balance after insertion?

A. By performing rotations and recoloring
B. By deleting the deepest node
C. By merging nodes
D. By increasing the height of the tree

Solution

Red-Black Trees maintain balance after insertion by performing rotations and recoloring nodes to satisfy the properties of the tree.

Correct Answer: A — By performing rotations and recoloring

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Q. How does an AVL tree maintain balance after an insertion?

A. By performing rotations.
B. By deleting nodes.
C. By increasing the height of the tree.
D. By changing node colors.

Solution

An AVL tree maintains balance after an insertion by performing rotations (single or double) to ensure the height difference property is satisfied.

Correct Answer: A — By performing rotations.

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Q. How does an AVL tree maintain balance after insertion?

A. By performing rotations.
B. By deleting nodes.
C. By increasing the height.
D. By changing colors.

Solution

AVL trees maintain balance by performing rotations (single or double) after insertions to ensure the balance factor remains within the allowed range.

Correct Answer: A — By performing rotations.

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Q. How does binary search determine the middle element of the array?

A. Using the first and last index
B. Using the average of all elements
C. Using the median value
D. Using a random index

Solution

Binary search calculates the middle element using the formula (low + high) / 2, where low and high are the current bounds.

Correct Answer: A — Using the first and last index

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Q. How does binary search determine the middle index of an array?

A. (low + high) / 2
B. low + high
C. low * high
D. high - low

Solution

Binary search calculates the middle index using (low + high) / 2 to find the midpoint of the current search range.

Correct Answer: A — (low + high) / 2

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Q. How does binary search determine the next interval to search?

A. By comparing the target with the middle element
B. By checking the first and last elements
C. By using a hash table
D. By traversing the entire array

Solution

Binary search determines the next interval by comparing the target with the middle element and deciding which half to continue searching.

Correct Answer: A — By comparing the target with the middle element

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Q. How does binary search determine which half of the array to search next?

A. By comparing the middle element with the target
B. By checking the length of the array
C. By using a random index
D. By iterating through the array

Solution

Binary search compares the middle element of the array with the target value to decide whether to search the left or right half.

Correct Answer: A — By comparing the middle element with the target

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Q. How does Dijkstra's algorithm ensure that it finds the shortest path?

A. By exploring all possible paths
B. By using a depth-first search
C. By always choosing the nearest unvisited vertex
D. By backtracking to previous nodes

Solution

Dijkstra's algorithm ensures it finds the shortest path by always choosing the nearest unvisited vertex, which is a key aspect of its greedy approach.

Correct Answer: C — By always choosing the nearest unvisited vertex

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Q. How does Dijkstra's algorithm ensure that the shortest path is found?

A. By exploring all possible paths
B. By using a greedy approach
C. By backtracking
D. By using dynamic programming

Solution

Dijkstra's algorithm uses a greedy approach, always expanding the least costly node first, ensuring that the shortest path is found.

Correct Answer: B — By using a greedy approach

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Q. How does Dijkstra's algorithm handle nodes that have already been visited?

A. It ignores them
B. It re-evaluates their distances
C. It adds them to a stack
D. It removes them from the graph

Solution

Once a node has been visited and its shortest distance determined, Dijkstra's algorithm ignores it in future iterations.

Correct Answer: A — It ignores them

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Q. How does Dijkstra's algorithm update the tentative distances of neighboring nodes?

A. By adding the edge weights to the current node's distance
B. By multiplying the edge weights with the current node's distance
C. By subtracting the edge weights from the current node's distance
D. By ignoring the edge weights

Solution

Dijkstra's algorithm updates the tentative distances of neighboring nodes by adding the edge weights to the current node's distance.

Correct Answer: A — By adding the edge weights to the current node's distance

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Q. How does Dijkstra's algorithm update the tentative distances?

A. By adding the edge weights to the current distances
B. By multiplying the edge weights with the current distances
C. By subtracting the edge weights from the current distances
D. By averaging the edge weights

Solution

Dijkstra's algorithm updates the tentative distances by adding the edge weights to the current distance of the node.

Correct Answer: A — By adding the edge weights to the current distances

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Data Structures & Algorithms

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