DSA Preparation (Python + Java)

This repository contains my step-by-step Data Structures and Algorithms (DSA) preparation using Python and Java.

The goal is to build strong programming fundamentals and then solve DSA problems with proper complexity analysis.

Repository Structure

DSA-Python-Java/
  Day_1/
    Day1.png
    Dsa_Day_1.pdf
    README.md
    python/
      day1_max_number.py
    java/
      Day1MaxNumber.java
  Day_2/
    Day2.png
    DSA_Day_2.pdf
    README.md
    python/
      day2_conditions.py
      day2_even_odd.py
      day2_pass_fail.py
      day2_voting_eligibility.py
      day2_largest_two.py
      day2_positive_negative_zero.py
    java/
      Day2Conditions.java
      Day2EvenOdd.java
      Day2PassFail.java
      Day2VotingEligibility.java
      Day2LargestTwo.java
      Day2PositiveNegativeZero.java
  Day_3/
    Day3.png
    DSA_Day_3.pdf
    README.md
    python/
      day3_loops.py
      day3_print_numbers.py
      day3_even_numbers.py
      day3_sum_natural.py
      day3_factorial.py
      day3_count_digits.py
    java/
      Day3Loops.java
      Day3PrintNumbers.java
      Day3EvenNumbers.java
      Day3SumNatural.java
      Day3Factorial.java
      Day3CountDigits.java
  Day_4/
    Day4.png
    DSA_Day_4.pdf
    README.md
    python/
      day4_patterns.py
      day4_square_star.py
      day4_right_triangle_star.py
      day4_number_triangle.py
      day4_reverse_triangle_star.py
      day4_square_number.py
    java/
      Day4Patterns.java
      Day4SquarePattern.java
      Day4RightTrianglePattern.java
      Day4NumberTriangle.java
      Day4ReverseTriangle.java
      Day4SquareNumberPattern.java

Day-wise Learning Journey

• Day 1 - Programming Basics, Complexity, Constraints
• Day 1 image (Day1.png) is attached as the first page of Dsa_Day_1.pdf
• Day 2 - Conditions, Comparison Operators, Logical Operators
• Day 2 image (Day2.png) is attached as the first page of DSA_Day_2.pdf
• Day 2 includes a LeetCode beginner practice plan focused on condition-based problems
• Day 3 - Loops, Loop Complexity, and Loop-Based Problems
• Day 3 includes beginner-friendly LeetCode links for loop-based practice
• Day 3 image (Day3.png) is attached as the first page of DSA_Day_3.pdf
• Day 4 - Pattern Problems and Nested Loops
• Day 4 includes nested-loop pattern practice in Python and Java
• Day 4 image (Day4.png) is attached as the first page of DSA_Day_4.pdf

Day 1 Highlights

Day 1 focuses on:

• Programming basics
• Python vs Java fundamentals
• Time Complexity and Big O Notation
• Space Complexity
• In-place algorithms
• Recursive stack space
• Using constraints to select the right approach

Problem Solving Rule Followed

1. Read constraints first.
2. Estimate time complexity.
3. Check if operations fit practical limits (around 10^8 operations).
4. Implement only the feasible approach.

Repository Goal

This repository will continue day by day with:

• DSA theory notes
• Python code examples
• Java code examples
• Practice problems
• Time and space complexity analysis