Data Structures Overview

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Questions and Answers

What characterizes an array in data structures?

It consists of elements that must be accessed sequentially.

It can hold items of different data types.

It is a sequential structure that allows random access. (correct)

It resembles a hierarchical structure.

Which data structure follows the LIFO principle?

Queue

Tree

Stack (correct)

Graph

In what way does a linked list differ from an array?

Arrays have a fixed size while linked lists can grow dynamically. (correct)

Arrays are always sequentially linked.

Linked lists allow random access to elements.

Linked lists can hold only one data type.

What type of structure is a tree in data structures?

Hierarchical structure Signup and view all the answers

Which statement accurately describes a queue?

It follows the First In First Out (FIFO) principle. Signup and view all the answers

What is contained within a graph structure in data structures?

A set of edges connecting elements. Signup and view all the answers

What is the main purpose of data structures in computer science?

To enhance the speed of data retrieval and storage. Signup and view all the answers

Which of the following statements about arrays is false?

Arrays allow for elements of different types to be stored. Signup and view all the answers

What operation is referred to when adding an element to a stack?

Push Signup and view all the answers

What does the peek() operation do in a stack?

Returns the top element without removing it Signup and view all the answers

Which of the following would indicate that a stack cannot accept any more elements?

isFull() returns true Signup and view all the answers

What happens during a stack underflow condition?

An attempt is made to remove an item from an empty stack Signup and view all the answers

Which structure can NOT be used to implement a stack?

Tree Signup and view all the answers

In which scenario would a stack experience overflow?

When an attempt is made to push an additional item onto a full stack Signup and view all the answers

What is the primary characteristic of linear data structures?

Data elements are arranged sequentially. Signup and view all the answers

What term describes the pointer that represents the last pushed data on the stack?

Top pointer Signup and view all the answers

Which of the following operations is NOT a basic stack operation?

Shift Signup and view all the answers

Which of the following is NOT an example of a non-linear data structure?

Queue Signup and view all the answers

What data structure is commonly used to implement an 'undo' mechanism in text editors?

Stack Signup and view all the answers

Which operation is used to combine the data items of two sorted files into a single sorted file?

Merging Signup and view all the answers

In terms of computer memory efficiency, which type of data structure is more efficient?

Non-linear data structure Signup and view all the answers

Which of the following is a typical use of arrays in data structures?

Searching for a specified target value Signup and view all the answers

Which operation is specifically defined as accessing each data item exactly once?

Traversing Signup and view all the answers

What data structure is effectively used in operating systems to maintain a disk's file system?

Graph Signup and view all the answers

What is the time complexity of an algorithm typically measured in?

The number of steps taken Signup and view all the answers

How does Big O notation aid in algorithm analysis?

It compares efficiency based on runtime growth Signup and view all the answers

What would be an example of a time-memory tradeoff?

Utilizing more memory to reduce computation time Signup and view all the answers

In C, how is the length of a string determined?

By counting all characters including the null character Signup and view all the answers

What part of an algorithm does time complexity refer to?

The time required to run the algorithm Signup and view all the answers

What does 'S(P) = 1 + 3' indicate in the provided algorithm?

One constant and three variables are used Signup and view all the answers

What does the null character ' ' indicate in a C string?

The termination of the string Signup and view all the answers

Why might someone prefer to solve a problem using more memory?

To save time in processing calculations Signup and view all the answers

What should a new node's next pointer point to when inserted between two nodes A and C?

RightNode Signup and view all the answers

What is the first step in the deletion operation of a node in a linked list?

Locate the target node to be removed. Signup and view all the answers

How does a header linked list manage the count of nodes?

By using a special node at the beginning. Signup and view all the answers

What characterizes a doubly linked list compared to a singly linked list?

It allows forward and backward navigation. Signup and view all the answers

In the context of a linked list, what does the term 'sequential search' refer to?

Searching for a node by comparing each node's value. Signup and view all the answers

What action should be taken after the previous node points to the next node of the target node during deletion?

Point the target node's next to NULL. Signup and view all the answers

Which of the following describes a situation where a new node is inserted at the end of a linked list?

The last node must connect to the new node. Signup and view all the answers

What is the purpose of the current pointer in a linked list search algorithm?

To compare with the key value on each iteration. Signup and view all the answers

What is the primary data structure used in Depth First Search (DFS)?

Stack Signup and view all the answers

Which step is NOT part of the DFS implementation process?

Insert vertices into a Queue Signup and view all the answers

What does a spanning tree produced by graph traversal represent?

A graph without loops Signup and view all the answers

What technique does Backtracking refer to in the context of graph traversal?

Returning to the previous vertex Signup and view all the answers

Which of the following describes the main purpose of Breadth First Search (BFS)?

To explore all vertices level by level Signup and view all the answers

What is the required action when a vertex at the front of the queue has no new adjacent vertices to visit in BFS?

Delete that vertex from the graph Signup and view all the answers

Which statement accurately characterizes the differences between DFS and BFS?

BFS uses a queue, while DFS uses a stack Signup and view all the answers

What must be ensured to avoid loops during graph traversal?

The traversal must track which vertices have been visited Signup and view all the answers

Study Notes

Data Structures

Data structure is a particular way to organize data in a computer so it can be used effectively.
Data structures are crucial in computer science for efficient handling of data in algorithms and software programs.

Examples of Data Structures

Arrays: Fixed-size structures holding items of the same data type (integers, floats, strings, etc.). Random access is possible.
Linked Lists: Sequential structures where items are linked to each other. Data access is sequential only, and random access is not possible.

Other Data Structures

Stacks: LIFO (Last-In, First-Out) structures, like a stack of plates. Elements are added and removed from the top.
Queues: FIFO (First-In, First-Out) structures, like a line of people waiting in a queue. Elements are added to the rear and removed from the front.
Trees: Hierarchical structures where data is organized in a parent-child relationship.
Graphs: Structures made of vertices (nodes) and edges connecting them, allowing for complex relationships between elements.

Elementary Data Organization

Data: An elementary value (e.g., student’s name, roll number).
Group Items: Data items with subordinate data items (e.g., a student's full name combining first and last names).
Records: Collections of data items. (e.g., a student's name, address, course, and marks).
Files: Collections of records. (example 60 employee records in a bank).
Entities: a person, place, thing, event, or concept about which information is stored. (e.g. employees in a bank).

Data Structures vs Data Types

Data Type: Describes pieces of data that share a common property (e.g., integer, character).
Data Structure: A way to organize data to more easily apply operations and algorithms (e.g., tree, array).

Categories of Data Structures

Primitive Data Structures: Data structures supported at the machine level (e.g., int, float, char, boolean).
Non-primitive Data Structures: Data structures derived from primitive data structures (e.g., Arrays, Linked Lists, Stacks, Queues, Trees, Graphs).
- Linear: Data elements are arranged sequentially (e.g., arrays, stacks, queues, linked lists).
- Non-linear: Data elements are not arranged sequentially (e.g., trees, graphs).

Data Structure Operations

Traversing: Accessing each data item exactly once.
Searching: Finding the location of a specific data item.
Inserting: Adding a new data item.
Deleting: Removing an existing data item.
Sorting: Arranging data items in a particular order (ascending, descending, or alphabetical).
Merging: Combining two sorted files into a single sorted file.

Applications of Data Structures

Searching and finding data: Efficiently locating specific data (e.g., minimum, maximum, average, mean, etc).
Undo in Text Editors: Stacks can keep track of edits for undo.
Job Scheduling and Disk Scheduling: Queues manage tasks and operations.
Symbol Tables: Linked Lists and Symbol Tables maintain a consistent format when managing parenthesis balance.
File Systems: Representing file folders as hierarchical tree structures.
Shortest Path Algorithms: Graphs are used for path calculation in Navigation systems, (maps, GPS)

Algorithms

An algorithm is a step-by-step procedure defining instructions that are performed in a certain order to get the desired result.
Characteristics of algorithms:
- Unambiguous: Clear and unambiguous instructions that lead to one meaning.
- Input: Zero or more well-defined inputs.
- Output: One or more well-defined outputs that match the expected output.
- Finiteness: Terminates after a finite number of steps.
- Feasibility: Should be feasible with available resources.
- Independence: Instructions are independent of programming code.

Algorithm Complexity

Time Factor: Measure of execution time by counting key operations.
Space Factor: Measure of memory space required by the algorithm.
The complexity of an algorithm (f(n)) describes running time (and/or storage) in terms of the size of input data (n).
Space Complexity: Amount of memory space an algorithm needs during its execution. (fixed portion/variable portion)

Big O Notation

Big O notation is used to describe the time complexity of an algorithm in terms of input size.
It expresses how quickly an algorithm's runtime grows as the input gets larger.

String Operations

strlen(): Computes a string's length.
strcpy(): Copies a string to another string.
strcat(): Concatenates two strings.
strcmp(): Compares two strings.
strlwr(): Converts a string to lowercase.
strupr(): Converts a string to uppercase.

Multi-dimensional Arrays

2D Arrays: Arrays with two dimensions (rows and columns).
3D Arrays: Arrays with three or more dimensions

Parallel Arrays

Several arrays of the same size, where elements in corresponding positions are related.

Sparse Matrices

Matrices with significantly more zero elements than non-zero elements, making them inefficient if stored as full 2D arrays.
Optimized storage representations, like Triplet Representation (arrays), exist to reduce storage space.

Linked Lists

Data structures in which data elements are not stored together. Data access is sequential.

Array vs. Linked Lists

Arrays: Efficient for random access, but less flexible when inserting or deleting.
Linked Lists: Efficient for insertion and deletion, but less time-efficient for random access.

Memory Representation of Queues

Using contiguous memory (like arrays): Data stored in a fixed-size array with FRONT and REAR pointers to track the front and rear of the queue.
Using non-contiguous memory (like a linked list): Data stored in nodes linked together using pointers, making the queue size dynamic.

Circular Queue

A queue where the last element points to the first.

Priority Queue

Extension of a queue where each item has a priority, and higher-priority items are served before lower-priority ones.

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Description

This quiz covers the fundamental concepts of data structures, including arrays, linked lists, stacks, queues, trees, and graphs. Understanding these structures is essential for effective data organization and algorithm implementation in computer science.