# 📘 Day 11 – Teacher's Day Challenge | String Task

🗓️ **Date:** August 04, 2025  
🧩 **Platform:** Codeforces  
🔢 **Problems Solved Today:** 1  
🎯 **Focus Topic:** Strings, Character Filtering, Case Handling

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🔗 **Table of Contents**

* [Problem 1 – String Task](https://codeforces.com/contest/118/problem/A)
    
* Daily Summary
    

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### 🧩 Problem 1 – String Task

📚 **Difficulty:** Easy  
🧠 **Concepts:** Character Iteration, Lowercasing, Vowel Removal, String Building

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📄 **Problem Statement (Summary):**  
Given a string with uppercase and lowercase Latin letters, perform the following:

* Remove all vowels (`A, O, Y, E, U, I` and lowercase variants).
    
* Convert all uppercase consonants to lowercase.
    
* Insert `.` before every consonant that remains.
    

Output the final processed string.

**Examples:**  
Input: `tour` → Output: `.t.r`  
Input: `Codeforces` → Output: `.c.d.f.r.c.s`  
Input: `aBAcAba` → Output: `.b.c.b`

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💡 **Approach:**

* Read input string.
    
* Iterate through each character:
    
    * Convert it to lowercase.
        
    * Skip if it’s a vowel.
        
    * Otherwise, append `"." + character"` to result.
        
* Print final result.
    

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🧪 **Code (C++):**

```cpp
#include <iostream>
#include <string>
#include <cctype>
#include <algorithm>
using namespace std;
int main()
{
    string str, result;
    cin >> str;

    for (char ch : str)
    {
        ch = tolower(ch);
        if (ch == 'a' || ch == 'o' || ch == 'y' || ch == 'e' || ch == 'u' || ch == 'i')
            continue;
        result += ".";
        result += ch;
    }
    cout << result;
    return 0;
}
```

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📸 **Submission Screenshot:**

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1754329428273/d383a761-dfb9-4543-a1ec-c98e6340e477.png align="center")

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1754329433179/f412217c-06e4-46f6-8025-33a427519fe0.png align="center")

![](https://cdn.hashnode.com/res/hashnode/image/upload/v1754329437219/f548c6a0-fe18-4836-8e7b-d1398684a8cc.png align="center")

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✅ **Key Takeaways:**

* `tolower()` simplifies case normalization.
    
* Filtering is easy using `continue` in loops.
    
* Vowels are explicitly checked; all others are treated as consonants.
    
* Concatenating strings in loops is fine for small input sizes.
    

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📈 **Daily Summary**

| Metric | Value |
| --- | --- |
| Problems Solved | 1 |
| Topics Covered | Strings, Case Handling |
| Tools Used | C++ |
| Next Focus | Frequency Maps, String Arrays |
| Day | 11 / 30 |

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🏷️ **Tags:**  
`#codeforces #strings #tolower #filtering #cpp #dsa #43DaysChallenge`