How to Master Arrays, Strings & Recursion for Placements in 30 Days

✅ 30-Day Plan to Master These Topics

Week 1: Get Comfortable with Arrays (Day 1–7)

Concepts to Learn:

• What is an array?

• Basic operations: traversal, insertion, deletion

• Finding min, max, sum, average

Practice Questions:

• Reverse an array

• Find max and min

• Sort an array

• Move all zeroes to the end

Tip: Try solving 2 easy problems daily from platforms like LeetCode, HackerRank, or Campusmonk.

Week 2: Master Array Patterns (Day 8–14)

Concepts to Learn:

• Two-pointer approach

• Sliding window technique

• Hashing in arrays

Practice Questions:

• Two sum

• Subarray with given sum

• Count pairs with given sum

• Find missing number

Tip: Focus on understanding the logic, not memorizing code. Write dry runs on paper.

Week 3: Learn String Basics + Patterns (Day 15–21)

Concepts to Learn:

• String manipulation basics

• Frequency count using arrays/dictionaries

• Palindrome and anagram logic

Practice Questions:

• Check if string is palindrome

• Remove duplicates

• Count vowels and consonants

• Find maximum occurring character

Tip: Start writing your own functions instead of using built-in ones immediately.

Week 4: Start Recursion (Day 22–27)

Concepts to Learn:

• What is recursion?

• Base case and recursive call

• Factorial, Fibonacci using recursion

Practice Questions:

• Factorial of a number

• Sum of digits using recursion

• Reverse a string using recursion

• Print subsets of a string

Tip: Recursion is tricky at first. Try drawing recursion trees to visualize the flow.

Final Days: Mock + Revision (Day 28–30)

Use these 3 days to:

• Revise all topics

• Re-solve the problems you got wrong earlier

• Take 2 mock coding rounds (30 mins each)

Tip: Don’t start new topics now. Focus on what you’ve already covered. Build confidence.