Lesson 3
Encoding Strings and Processing Arrays in Parallel
Introduction

Welcome to an exciting exploration of string manipulation and array operations! In this Unit, we’ll tackle a unique challenge: processing a string and an array in parallel while adhering to specific conditions. This engaging task is part of a mysterious book club's cryptic coding adventure.

Get ready to uncover the secrets of combining string and numerical logic into one seamless solution!

Task Statement

Our goal is to create a unique encoded message and manage an array of numbers simultaneously. Here's what we need to do:

  1. Replace each letter in a string with the next letter alphabetically. If the letter is 'z', wrap around to 'a'.
  2. For an accompanying array of numbers, divide each number by 2, round the result, and accumulate these rounded values.
  3. Stop processing once the accumulated sum exceeds 20.
  4. Reverse the updated string to complete the cryptic transformation.
  5. Return the reversed string and the unprocessed numbers from the array.

For example, given the input string "books" and the array [10, 20, 30, 50, 100]:

  • Start with an empty string and a sum of 0.
  • Process 'b' (becomes 'c') and 10 (half is 5), sum becomes 5.
  • Process 'o' (becomes 'p') and 20 (half is 10), sum becomes 15.
  • Process 'o' (becomes 'p') and 30 (half is 15), sum becomes 30, exceeding 20. Stop processing.

The resulting string is "cpp", reversed to "ppc". The unprocessed numbers are [50, 100].

The output will be:

Ruby
1["ppc", [50, 100]]
Solution Building: Step 1 - Initialization

We begin by setting up our components: the result string to store the transformed characters, a variable to track the cumulative sum, and an index to keep track of how many elements have been processed.

Ruby
1def generate_cryptic_message(input_string, numbers) 2 result = '' # Holds the processed characters 3 sum_so_far = 0 # Tracks the cumulative sum of half numbers 4 index = 0 # Tracks how many elements have been processed

With these initialized, we are ready to start processing the input.

Solution Building: Step 2 - Processing the String and Array

Next, we iterate over the characters in the input string along with their corresponding numbers. For each character:

  • Replace it with the next alphabetical character, wrapping around from 'z' to 'a'.
  • Append the transformed character to the result string.
  • Divide the corresponding number by 2, round it, and add the result to the cumulative sum.
  • Stop processing as soon as the sum exceeds 20.
Ruby
1 input_string.each_char.with_index do |char, i| 2 shifted_char = char == 'z' ? 'a' : (char.ord + 1).chr 3 result += shifted_char 4 5 half_number = (numbers[i] / 2.0).round 6 sum_so_far += half_number 7 index = i + 1 # Update the index to reflect processed characters 8 9 break if sum_so_far > 20 # Stop processing if the sum exceeds 20 10 end

At this stage, we have a partially processed string and a cumulative sum that determines how far we’ve gone.

Solution Building: Step 3 - Final Adjustments and Return

With the processing complete, we finalize the result string by reversing it to complete the encoding. Then, we determine the remaining unprocessed numbers in the array, starting from the index where the loop stopped.

Ruby
1 reversed_result = result.reverse # Reverse the processed string 2 remaining_numbers = numbers[index..-1] || [] # Extract unprocessed numbers 3 4 [reversed_result, remaining_numbers] # Return the final results 5end

The reversed string and the remaining numbers are now ready to be returned as the output.

Full Implementation

Here’s the complete implementation of the solution:

Ruby
1def generate_cryptic_message(input_string, numbers) 2 result = '' # Holds the processed characters 3 sum_so_far = 0 # Tracks the cumulative sum of half numbers 4 index = 0 # Tracks how many elements have been processed 5 6 input_string.each_char.with_index do |char, i| 7 shifted_char = char == 'z' ? 'a' : (char.ord + 1).chr 8 result += shifted_char 9 10 half_number = (numbers[i] / 2.0).round 11 sum_so_far += half_number 12 index = i + 1 # Update the index to reflect processed characters 13 14 break if sum_so_far > 20 # Stop processing if the sum exceeds 20 15 end 16 17 reversed_result = result.reverse # Reverse the processed string 18 remaining_numbers = numbers[index..-1] || [] # Extract unprocessed numbers 19 20 [reversed_result, remaining_numbers] # Return the final results 21end
Lesson Summary

Congratulations! You’ve successfully implemented a solution that combines string manipulation and numerical processing into a cohesive algorithm. This task demonstrated how to handle parallel operations efficiently and stop dynamically based on a condition.

These skills are essential for solving complex problems that blend logic and creativity. Keep practicing, and happy coding!

Enjoy this lesson? Now it's time to practice with Cosmo!
Practice is how you turn knowledge into actual skills.