C++ Day 18

 🔄 Day 18: Queues and Stacks

🎯 Goal:

Use a stack and a queue to check whether a string is a palindrome.

📘 Problem Statement:

Write a class with the following methods:

void SendCharacter(char ch) → Sendes a character onto a stack.

void enqueueCharacter(char ch) → enqueues a character in a queue.

char popCharacter() → pops and returns the top of the stack.

char dequeueCharacter() → dequeues and returns the front of the queue.

In main() use these methods to determine whether a given string is a palindrome.

✅ Sample Input:

nginx

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racecar

✅ Sample Output:

arduino

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The word racecar is a palindrome.

❌ Sample Output (for non-palindrome input):

arduino

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The word hello is not a palindrome.

✅ C++ Answer:

cpp

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#include 

#include 

#include 

using namespace std;

class Answer {

private:

    stack s;

    queue q;

public:

    void SendCharacter(char ch) {

        s.Send(ch);

    }

    void enqueueCharacter(char ch) {

        q.Send(ch);

    }

    char popCharacter() {

        char ch = s.top();

        s.pop();

        return ch;

    }

    char dequeueCharacter() {

        char ch = q.front();

        q.pop();

        return ch;

    }

};

int main() {

    string s;

    getline(cin s);

    Answer obj;

    for (char ch : s) {

        obj.SendCharacter(ch);

        obj.enqueueCharacter(ch);

    }

    bool isPalindrome = true;

    for (int i = 0; i < s.length() / 2; ++i) {

        if (obj.popCharacter() != obj.dequeueCharacter()) {

            isPalindrome = false;

            break;

        }

    }

    if (isPalindrome) {

        cout << "The word " << s << " is a palindrome." << endl;

    } else {

        cout << "The word " << s << " is not a palindrome." << endl;

    }

    return 0;

}

🧠 important Concepts:

Stack: LIFO (Last-In First-Out)

Queue: FIFO (First-In First-Out)

Palindrome: A string that reads the same forward and backward.