📘 Day 17 – Teacher's Day Challenge | Stones on the Table

🗓️ Date: August 10, 2025
🧩 Platform: Codeforces
🔢 Problems Solved Today: 1
🎯 Focus Topic: Strings, Consecutive Characters

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🔗 Table of Contents

• Problem 1 – Stones on the Table

• Daily Summary

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🧩 Problem 1 – Stones on the Table

📚 Difficulty: Easy-Medium
🧠 Concepts: Strings, Counting Consecutive Elements

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📄 Problem Statement (Summary):
You are given n stones in a row, each stone being Red (R), Green (G), or Blue (B).
You must find the minimum number of stones to remove so that no two neighboring stones have the same color.

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🔢 Input Format:

• First line: integer n (1 ≤ n ≤ 50) – number of stones.

• Second line: string s of length n, where s[i] ∈ {R, G, B}.

🧾 Output Format:
A single integer – minimum stones to remove.

🔍 Example 1:
Input:

3  
RRG

Output:

1

🔍 Example 2:
Input:

5  
RRRRR

Output:

4

🔍 Example 3:
Input:

4  
BRBG

Output:

0

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💡 Approach:

• Traverse the string from left to right.

• Count every instance where s[i] == s[i+1] (two consecutive same colors).

• This count is the minimum stones to remove.

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🧪 Code (C++):

#include <iostream>
using namespace std;

int main() {
    int n, c1=0;
    cin >> n;
    string s;
    cin >> s;

    for (int i = 0; i < n - 1; i++) {
        if (s[i] == s[i + 1]) {
            c1++;
        }
    }

    cout << c1 << endl;
    return 0;
}

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📸 Submission Screenshot:

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✅ Key Takeaways:

• Simple linear scan solves the problem efficiently.

• Always remember n-1 in loop to avoid out-of-bounds errors.

• Problems with small constraints often just require careful counting logic.

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📈 Daily Summary

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🏷️ Tags:
#codeforces #strings #cpp #beginner #dsa #43DaysChallenge