Complete DSA Roadmap

|-- Basic_Data_Structures
| |-- Arrays
| |-- Strings
| |-- Linked_Lists
| |-- Stacks
| └─ Queues
|
|-- Advanced_Data_Structures
| |-- Trees
| | |-- Binary_Trees
| | |-- Binary_Search_Trees
| | |-- AVL_Trees
| | └─ B-Trees
| |
| |-- Graphs
| | |-- Graph_Representation
| | | |- Adjacency_Matrix
| | | └ Adjacency_List
| | |
| | |-- Depth-First_Search
| | |-- Breadth-First_Search
| | |-- Shortest_Path_Algorithms
| | | |- Dijkstra's_Algorithm
| | | └ Bellman-Ford_Algorithm
| | |
| | └─ Minimum_Spanning_Tree
| | |- Prim's_Algorithm
| | └ Kruskal's_Algorithm
| |
| |-- Heaps
| | |-- Min_Heap
| | |-- Max_Heap
| | └─ Heap_Sort
| |
| |-- Hash_Tables
| |-- Disjoint_Set_Union
| |-- Trie
| |-- Segment_Tree
| └─ Fenwick_Tree
|
|-- Algorithmic_Paradigms
| |-- Brute_Force
| |-- Divide_and_Conquer
| |-- Greedy_Algorithms
| |-- Dynamic_Programming
| |-- Backtracking
| |-- Sliding_Window_Technique
| |-- Two_Pointer_Technique
| └─ Divide_and_Conquer_Optimization
| |-- Merge_Sort_Tree
| └─ Persistent_Segment_Tree
|
|-- Searching_Algorithms
| |-- Linear_Search
| |-- Binary_Search
| |-- Depth-First_Search
| └─ Breadth-First_Search
|
|-- Sorting_Algorithms
| |-- Bubble_Sort
| |-- Selection_Sort
| |-- Insertion_Sort
| |-- Merge_Sort
| |-- Quick_Sort
| └─ Heap_Sort
|
|-- Graph_Algorithms
| |-- Depth-First_Search
| |-- Breadth-First_Search
| |-- Topological_Sort
| |-- Strongly_Connected_Components
| └─ Articulation_Points_and_Bridges
|
|-- Dynamic_Programming
| |-- Introduction_to_DP
| |-- Fibonacci_Series_using_DP
| |-- Longest_Common_Subsequence
| |-- Longest_Increasing_Subsequence
| |-- Knapsack_Problem
| |-- Matrix_Chain_Multiplication
| └─ Dynamic_Programming_on_Trees
|
|-- Mathematical_and_Bit_Manipulation_Algorithms
| |-- Prime_Numbers_and_Sieve_of_Eratosthenes
| |-- Greatest_Common_Divisor
| |-- Least_Common_Multiple
| |-- Modular_Arithmetic
| └─ Bit_Manipulation_Tricks
|
|-- Advanced_Topics
| |-- Trie-based_Algorithms
| | |-- Auto-completion
| | └─ Spell_Checker
| |
| |-- Suffix_Trees_and_Arrays
| |-- Computational_Geometry
| |-- Number_Theory
| | |-- Euler's_Totient_Function
| | └─ Mobius_Function
| |
| └─ String_Algorithms
| |-- KMP_Algorithm
| └─ Rabin-Karp_Algorithm
|
|-- OnlinePlatforms
| |-- LeetCode
| |-- HackerRank

Here are some essential SQL tips for beginners 👇👇

◆ Primary Key = Unique Key + Not Null constraint
◆ To perform case insensitive search use UPPER() function ex. UPPER(customer_name) LIKE ‘A%A’
◆ LIKE operator is for string data type
◆ COUNT(*), COUNT(1), COUNT(0) all are same
◆ All aggregate functions ignore the NULL values
◆ Aggregate functions MIN, MAX, SUM, AVG, COUNT are for int data type whereas STRING_AGG is for string data type
◆ For row level filtration use WHERE and aggregate level filtration use HAVING
◆ UNION ALL will include duplicates where as UNION excludes duplicates 
◆ If the results will not have any duplicates, use UNION ALL instead of UNION
◆ We have to alias the subquery if we are using the columns in the outer select query
◆ Subqueries can be used as output with NOT IN condition.
◆ CTEs look better than subqueries. Performance wise both are same.
◆ When joining two tables , if one table has only one value then we can use 1=1 as a condition to join the tables. This will be considered as CROSS JOIN.
◆ Window functions work at ROW level.
◆ The difference between RANK() and DENSE_RANK() is that RANK() skips the rank if the values are the same.
◆ EXISTS works on true/false conditions. If the query returns at least one value, the condition is TRUE. All the records corresponding to the conditions are returned.

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Here are 20 essential VS Code shortcuts for beginners:

1. Ctrl + P: Open any file quickly 📂

2. Ctrl + /: Toggle line comment 📝

3. Alt + Up/Down: Move a line up or down ↕️

4. Ctrl + Shift + K: Delete the current line ❌

5. Ctrl + B: Show/hide the sidebar 📚

6. Ctrl + Space: Trigger IntelliSense for code suggestions 💡

7. Ctrl + Shift + F: Search across files 🔍

8. Ctrl + D: Select the next occurrence of the selected text 📑

9. Ctrl + Shift + L: Select all occurrences of the current selection 🔗

10. Ctrl + Shift + P: Open the Command Palette 📜

11. Ctrl + F2: Rename all occurrences of a variable ✏️

12. Ctrl + J: Show/hide the integrated terminal 💻

13. Ctrl + `: Open a new terminal 🔧

14. Ctrl + Shift + N: Open a new window 🖼️

15. Ctrl + W: Close the current editor tab 🗂️

16. Ctrl + Shift + E: Focus on the file explorer 🗃️

17. Ctrl + Shift + G: Open the Git view 🔄

18. Ctrl + Shift + M: Open the Problems panel 🚨

19. Alt + Shift + Up/Down: Copy the line up or down 📋

20. Ctrl + Alt + Arrow keys: Split the editor window ✂️


Master these and level up your coding speed! 🚀

9 tips to prepare for coding interviews:

Master DSA fundamentals (arrays, strings, trees, graphs)

Practice daily on LeetCode, Codeforces, or HackerRank

Solve problems under time constraints

Review commonly asked interview patterns

Mock interviews help reduce anxiety

Understand the “why” behind each solution

Prepare clean, structured explanations

Brush up on system design and OOP basics

Stay consistent — prep a little every day

Coding Interview Resources:👇 https://whatsapp.com/channel/0029VammZijATRSlLxywEC3X

ENJOY LEARNING 👍👍

In 1994, people told me programming was for nerds and that I should become a doctor or a lawyer instead.

10 years later, they told me that someone from India would take my job for $5/hour.

Then, no code was going to doom my career.

In 2021, Codex, then Copilot, then ChatGPT, then Devin, then OpenAI o1...

People keep yelling that "Programming is Dead," and yet the demand for good Software Engineers has never been higher.

Stop listening to midwit people. Learn to build good software, and you'll be okay. (Credits: unknown)

Best way to prepare for a SQL interviews 👇👇

1. Review Basic Concepts: Ensure you understand fundamental SQL concepts like SELECT statements, JOINs, GROUP BY, and WHERE clauses.

2. Practice SQL Queries: Work on writing and executing SQL queries. Practice retrieving, updating, and deleting data.

3. Understand Database Design: Learn about normalization, indexes, and relationships to comprehend how databases are structured.

4. Know Your Database: If possible, find out which database system the company uses (e.g., MySQL, PostgreSQL, SQL Server) and familiarize yourself with its specific syntax.

5. Data Types and Constraints: Understand various data types and constraints such as PRIMARY KEY, FOREIGN KEY, and UNIQUE constraints.

6. Stored Procedures and Functions: Learn about stored procedures and functions, as interviewers may inquire about these.

7. Data Manipulation Language (DML): Be familiar with INSERT, UPDATE, and DELETE statements.

8. Data Definition Language (DDL): Understand statements like CREATE, ALTER, and DROP for database and table management.

9. Normalization and Optimization: Brush up on database normalization and optimization techniques to demonstrate your understanding of efficient database design.

10. Troubleshooting Skills: Be prepared to troubleshoot queries, identify errors, and optimize poorly performing queries.

11. Scenario-Based Questions: Practice answering scenario-based questions. Understand how to approach problems and design solutions.

12. Latest Trends: Stay updated on the latest trends in database technologies and SQL best practices.

13. Review Resume Projects: If you have projects involving SQL on your resume, be ready to discuss them in detail.

14. Mock Interviews: Conduct mock interviews with a friend or use online platforms to simulate real interview scenarios.

15. Ask Questions: Prepare questions to ask the interviewer about the company's use of databases and SQL.

Best Resources to learn SQL 👇

SQL Topics for Data Analysts

SQL Udacity Course

Download SQL Cheatsheet

SQL Interview Questions

Learn & Practice SQL

Also try to apply what you learn through hands-on projects or challenges.

Please give us credits while sharing: -> https://t.iss.one/free4unow_backup

ENJOY LEARNING 👍👍

The Only roadmap you need to become an ML Engineer 🥳

Phase 1: Foundations (1-2 Months)
🔹 Math & Stats Basics – Linear Algebra, Probability, Statistics
🔹 Python Programming – NumPy, Pandas, Matplotlib, Scikit-Learn
🔹 Data Handling – Cleaning, Feature Engineering, Exploratory Data Analysis

Phase 2: Core Machine Learning (2-3 Months)
🔹 Supervised & Unsupervised Learning – Regression, Classification, Clustering
🔹 Model Evaluation – Cross-validation, Metrics (Accuracy, Precision, Recall, AUC-ROC)
🔹 Hyperparameter Tuning – Grid Search, Random Search, Bayesian Optimization
🔹 Basic ML Projects – Predict house prices, customer segmentation

Phase 3: Deep Learning & Advanced ML (2-3 Months)
🔹 Neural Networks – TensorFlow & PyTorch Basics
🔹 CNNs & Image Processing – Object Detection, Image Classification
🔹 NLP & Transformers – Sentiment Analysis, BERT, LLMs (GPT, Gemini)
🔹 Reinforcement Learning Basics – Q-learning, Policy Gradient

Phase 4: ML System Design & MLOps (2-3 Months)
🔹 ML in Production – Model Deployment (Flask, FastAPI, Docker)
🔹 MLOps – CI/CD, Model Monitoring, Model Versioning (MLflow, Kubeflow)
🔹 Cloud & Big Data – AWS/GCP/Azure, Spark, Kafka
🔹 End-to-End ML Projects – Fraud detection, Recommendation systems

Phase 5: Specialization & Job Readiness (Ongoing)
🔹 Specialize – Computer Vision, NLP, Generative AI, Edge AI
🔹 Interview Prep – Leetcode for ML, System Design, ML Case Studies
🔹 Portfolio Building – GitHub, Kaggle Competitions, Writing Blogs
🔹 Networking – Contribute to open-source, Attend ML meetups, LinkedIn presence

Follow this advanced roadmap to build a successful career in ML!

The data field is vast, offering endless opportunities so start preparing now.

Python Interview Questions:

Ready to test your Python skills? Let’s get started! 💻


1. How to check if a string is a palindrome?

def is_palindrome(s):
    return s == s[::-1]

print(is_palindrome("madam"))  # True
print(is_palindrome("hello"))  # False

2. How to find the factorial of a number using recursion?

def factorial(n):
    if n == 0 or n == 1:
        return 1
    return n * factorial(n - 1)

print(factorial(5))  # 120

3. How to merge two dictionaries in Python?

dict1 = {'a': 1, 'b': 2}
dict2 = {'c': 3, 'd': 4}

# Method 1 (Python 3.5+)
merged_dict = {**dict1, **dict2}

# Method 2 (Python 3.9+)
merged_dict = dict1 | dict2

print(merged_dict)

4. How to find the intersection of two lists?

list1 = [1, 2, 3, 4]
list2 = [3, 4, 5, 6]

intersection = list(set(list1) & set(list2))
print(intersection)  # [3, 4]

5. How to generate a list of even numbers from 1 to 100?

even_numbers = [i for i in range(1, 101) if i % 2 == 0]
print(even_numbers)

6. How to find the longest word in a sentence?

def longest_word(sentence):
    words = sentence.split()
    return max(words, key=len)

print(longest_word("Python is a powerful language"))  # "powerful"

7. How to count the frequency of elements in a list?

from collections import Counter

my_list = [1, 2, 2, 3, 3, 3, 4]
frequency = Counter(my_list)
print(frequency)  # Counter({3: 3, 2: 2, 1: 1, 4: 1})

8. How to remove duplicates from a list while maintaining the order?

def remove_duplicates(lst):
    return list(dict.fromkeys(lst))

my_list = [1, 2, 2, 3, 4, 4, 5]
print(remove_duplicates(my_list))  # [1, 2, 3, 4, 5]

9. How to reverse a linked list in Python?

class Node:
    def __init__(self, data):
        self.data = data
        self.next = None

def reverse_linked_list(head):
    prev = None
    current = head
    while current:
        next_node = current.next
        current.next = prev
        prev = current
        current = next_node
    return prev

# Create linked list: 1 -> 2 -> 3
head = Node(1)
head.next = Node(2)
head.next.next = Node(3)

# Reverse and print the list
reversed_head = reverse_linked_list(head)
while reversed_head:
    print(reversed_head.data, end=" -> ")
    reversed_head = reversed_head.next

10. How to implement a simple binary search algorithm?

def binary_search(arr, target):
    low, high = 0, len(arr) - 1
    while low <= high:
        mid = (low + high) // 2
        if arr[mid] == target:
            return mid
        elif arr[mid] < target:
            low = mid + 1
        else:
            high = mid - 1
    return -1

print(binary_search([1, 2, 3, 4, 5, 6, 7], 4))  # 3

Here you can find essential Python Interview Resources👇
https://t.iss.one/DataSimplifier

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Share with credits: https://t.iss.one/sqlspecialist

Hope it helps :)

Java coding interview questions

1. Reverse a String:
Write a Java program to reverse a given string.
2. Find the Largest Element in an Array:
Find and print the largest element in an array.
3. Check for Palindrome:
Determine if a given string is a palindrome (reads the same backward as forward).
4. Factorial Calculation:
Write a function to calculate the factorial of a number.
5. Fibonacci Series:
Generate the first n numbers in the Fibonacci sequence.
6. Check for Prime Number:
Write a program to check if a given number is prime.
7. String Anagrams:
Determine if two strings are anagrams of each other.

8. Array Sorting:
Implement sorting algorithms like bubble sort, merge sort, or quicksort.

9. Binary Search:
Implement a binary search algorithm to find an element in a sorted array.

10. Duplicate Elements in an Array:
Find and print duplicate elements in an array.

11. Linked List Reversal:
Reverse a singly-linked list.

12. Matrix Operations:
Perform matrix operations like addition, multiplication, or transpose.

13. Implement a Stack:
Create a stack data structure and implement basic operations (push, pop).

14. Implement a Queue:
Create a queue data structure and implement basic operations (enqueue, dequeue).

15. Inheritance and Polymorphism:
Implement a class hierarchy with inheritance and demonstrate polymorphism.

16. Exception Handling:
Write code that demonstrates the use of try-catch blocks to handle exceptions.
17. File I/O:
Read from and write to a file using Java's file I/O capabilities.
18. Multithreading:
Create a simple multithreaded program and demonstrate thread synchronization.
19. Lambda Expressions:
Use lambda expressions to implement functional interfaces.
20. Recursive Algorithms:
Solve a problem using recursion, such as computing the factorial or Fibonacci sequence.

Best Java Resources: https://whatsapp.com/channel/0029VamdH5mHAdNMHMSBwg1s

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Commonly asked System Design CONCEPT BASED interview topics -

1. Horizontal vs Vertical Partitioning:
Vertical partitioning splits tables by columns, often separating different features. Horizontal partitioning splits tables by rows, distributing data across multiple servers. Vertical organizes data logically, while horizontal improves scalability + performance.

2. Apache Kafka:
Kafka is a distributed streaming platform using a publish-subscribe model. It's fast due to the sequential disk I/O, zero-copy principle, and efficient batching of messages.

3. Rate Limiter:
A rate limiter controls the rate of requests a client can make to a service. It prevents overload and ensures fair resource usage.

4. JWT vs OAuth vs SAML:
JWT is a compact, self-contained token for secure information transmission. OAuth is an authorization framework for delegated access. SAML is an XML-based standard for exchanging authentication and authorization data.

5. Single Sign-On (SSO):
SSO allows users to access multiple applications with one set of credentials. It typically uses a central authentication server and protocols like SAML/OAuth.

6. Microservices vs Monolithic Architecture:
Microservices architecture breaks an application into small, independent services. Monolithic architecture is a single, tightly-coupled unit. Microservices offer scalability while monoliths are simpler to develop + deploy.

7. Reverse Proxy vs Forward Proxy:
A reverse proxy sits in front of web servers, forwarding client requests to backend servers. A forward proxy sits in front of clients, forwarding their requests to the internet. Reverse proxies are used for load balancing and security, while forward proxies are used for anonymity and filtering.

8. CAP Theorem:
The CAP theorem states that a distributed system can only provide two of three guarantees: Consistency, Availability, and Partition tolerance. In practice, partition tolerance is necessary, so systems must choose between consistency and availability during network partitions.

10. Efficient Caching Strategy:
Implement multi-level caching (browser, CDN, application server, database). Use appropriate cache invalidation strategies (TTL, event-based). Consider cache coherence for distributed systems.

Best DSA RESOURCES: https://topmate.io/coding/886874

All the best 👍👍