Module 2, Technical Preparation: Palindromes

Module 2 focuses on solving palindrome-related problems, a common type of challenge in technical interviews and coding assessments. A palindrome is a word, phrase, number, or other sequence of characters that reads the same forward and backward (ignoring spaces, punctuation, and capitalization).

Through this module, you'll learn various techniques to identify, validate, and manipulate palindromes, strengthening your string manipulation skills and problem-solving abilities.

What are Palindromes?

A palindrome is a sequence that reads the same backward as forward. This concept applies to:

• Words: "radar", "level", "madam"
• Phrases: "A man, a plan, a canal, Panama" (ignoring spaces, commas, and case)
• Numbers: 121, 1001, 12321

Why are Palindromes Important in Technical Interviews?

Palindrome problems are popular in technical interviews because they:

• Test your string manipulation skills
• Can be solved with various approaches (iteration, recursion)
• Often involve edge cases that test your attention to detail
• Can be extended to more complex variants that test algorithmic thinking

Two-Pointer Technique

The most efficient approach for checking palindromes is using the two-pointer technique:

1. Place one pointer at the beginning of the string
2. Place another pointer at the end of the string
3. Move the pointers toward each other, comparing characters
4. If any characters don't match, it's not a palindrome
5. If the pointers meet or cross without finding mismatches, it is a palindrome

Reverse and Compare

Another common approach is to reverse the string and compare:

1. Create a reversed copy of the string
2. Compare the original string with the reversed string
3. If they're identical, it's a palindrome

While this approach is intuitive, it requires extra space for the reversed string.

Advanced Palindrome Challenges

More complex palindrome problems may involve:

• Finding palindromic substrings
• Creating palindromes by rearranging characters
• Determining the minimum insertions needed to make a string palindromic
• Checking if a linked list is palindromic

In this guided project, you'll apply your understanding of palindromes and the problem-solving framework to solve string manipulation challenges. You'll work through palindrome validation problems step-by-step, building your skills in string processing and algorithm implementation.

Project Resources

GCA Preparation - General Practice

As part of this module, you'll continue practicing for the General Code Assessment (GCA). Building on the problem-solving skills from Module 1, you'll now focus on string manipulation and palindrome challenges:

1. Go to the LeetCode Problems section
2. Attempt at least 10 problems on your own, applying the 4-step problem-solving framework
3. Focus on problems involving string manipulation and palindromes
4. Pay special attention to the "Understand" phase, ensuring you identify all edge cases

Regular practice is essential for success on the GCA. Focusing on palindrome problems will help you build critical string manipulation skills needed for the assessment.

Recommended LeetCode Problems

The following medium-difficulty problems will help you practice applying the problem-solving framework to palindrome and string manipulation scenarios:

• Valid Palindrome - Basic palindrome check with character filtering
• Valid Palindrome II - Checking if a string can become palindromic by removing one character
• Palindromic Substrings - Count how many palindromic substrings are in a string
• Longest Palindromic Substring - Find the longest palindromic substring
• Palindrome Partitioning - Partition a string such that every substring is a palindrome

To reinforce your understanding of palindromes, complete the following activities:

1. Choose at least 3 problems from the recommended list above
2. For each problem:
   • Apply the four-step problem-solving framework
   • Document your thought process for each step
   • Implement both the two-pointer approach and the reverse-and-compare approach (where applicable)
   • Compare the efficiency of different approaches in terms of time and space complexity
   • After solving, review the Discussion section to see different approaches
3. Create your own palindrome challenge and share it with peers
4. Practice explaining your approach as if you were in a technical interview

As part of this module, you will continue to prepare for the official General Code Assessment (GCA) test on CodeSignal. This standardized assessment evaluates your coding skills and provides a score that reflects your programming proficiency.

About the GCA:

• The assessment consists of 4 programming tasks to complete in 70 minutes
• You should aim for a score of 295 or higher
• Your highest score is tracked in the BloomTech database

Taking the GCA:

1. Take the official GCA at this link: BloomTech GCA Test

Remember: Regular practice on LeetCode problems using the 4-step problem-solving framework will help you succeed on the GCA. Focus on understanding problems thoroughly before implementing solutions.