Discussion on 'Toggle String' (Problem from HackerEarth)

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Problem
You have been given a String S consisting of uppercase and lowercase English alphabets. You need to change the case of each alphabet in this String. That is, all the uppercase letters should be converted to lowercase and all the lowercase letters should be converted to uppercase. You need to then print the resultant String to output.

Input Format
The first and only line of input contains the String S

Output Format
Print the resultant String on a single line.

Constraints
1 <= length(S) <= 100 

Sample Input
abcdE
Sample Output
ABCDe

Psuedo code

t = ""
for i in S:
    if i.isupper():
        t += i.lower()
    else:
        t += i.upper()

Critique this psuedo code.

Critique by ChatGPT

Your pseudocode is clear, correct, and solves the problem as intended — it swaps the case of each letter in the string. Here's a detailed critique of its strengths and a few potential improvements:

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✅ Strengths

1. Correct Logic:

   • It checks each character: if it’s uppercase, it converts to lowercase, and vice versa.

   • This aligns exactly with the problem requirements.

2. Readable and Intuitive:

   • Simple variable names like t and i, and clear conditionals make the code easy to follow.

3. Character-wise Traversal:

   • Traversing each character individually ensures all characters are handled properly.

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⚠️ Possible Improvements

1. Performance Consideration (String Concatenation in Loop)

   • Strings in Python are immutable, so doing t += i.upper() repeatedly creates a new string at every step, which can be inefficient in longer strings.

   • Better Approach: Use a list to build characters, then join:

     python
     result = []
     for i in S:
         if i.isupper():
             result.append(i.lower())
         else:
             result.append(i.upper())
     t = ''.join(result)
     

2. Better Variable Naming

   • t and i are fine for pseudocode, but in actual code, consider using:

     • char instead of i

     • result instead of t

   • Improves readability, especially for beginners or interviews.

3. Alternative Built-in Method

   • Python has a built-in method: str.swapcase() which does exactly this. For real-world use:

     python
     print(S.swapcase())
     

   • However, since you're showing your logic manually (perhaps for an interview or educational context), it's good to write it out.

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✅ Verdict:

Your pseudocode is functionally correct and clear, but could be slightly optimized for performance and readability in actual implementation. Great job!