﻿ C++ Check if two queues are equal

# C++ Queue Exercises: Check if two queues are equal

## C++ Queue: Exercise-25 with Solution

Write a C++ program to check if two queues are equal.

Sample Solution:

C Code:

``````#include <iostream> // Including necessary library for input and output operations

using namespace std;

const int MAX_SIZE = 100; // Maximum size for the queue

class Queue {
private:
int front; // Front of the queue
int rear; // Rear of the queue
int arr[MAX_SIZE]; // Array to store queue elements

public:
Queue() {
front = -1; // Initializing front index to -1
rear = -1; // Initializing rear index to -1
}

bool isFull() {
return (rear == MAX_SIZE - 1); // Check if the queue is full
}

bool isEmpty() {
return (front == -1 && rear == -1); // Check if the queue is empty
}

void enqueue(int x) {
if (isFull()) {
cout << "Error: Queue is full" << endl; // Display error if the queue is full
return;
}
if (isEmpty()) {
front = 0;
rear = 0;
} else {
rear++;
}
arr[rear] = x; // Add an element to the rear of the queue
}

void dequeue() {
if (isEmpty()) {
cout << "Error: Queue is empty" << endl; // Display error if the queue is empty
return;
}
if (front == rear) {
front = -1;
rear = -1;
} else {
front++;
}
}

int peek() {
if (isEmpty()) {
cout << "Error: Queue is empty" << endl; // Display error if the queue is empty
return -1;
}
return arr[front]; // Return the element at the front of the queue
}

bool isEqual(Queue q1, Queue q2) {
if (q1.isEmpty() && q2.isEmpty()) {
return true; // Return true if both queues are empty
}
if (q1.isEmpty() || q2.isEmpty()) {
return false; // Return false if only one of the queues is empty
}
if (q1.peek() != q2.peek()) {
return false; // Return false if the front elements of the queues are not equal
}
Queue temp1 = q1;
Queue temp2 = q2;
while (!temp1.isEmpty() && !temp2.isEmpty()) {
if (temp1.peek() != temp2.peek()) {
return false; // Return false if any corresponding elements of queues are not equal
}
temp1.dequeue();
temp2.dequeue();
}
return (temp1.isEmpty() && temp2.isEmpty()); // Return true if both queues are empty after comparisons
}

void display() {
if (isEmpty()) {
cout << "Error: Queue is empty" << endl; // Display error if the queue is empty
return;
}
cout << "Queue elements are: ";
for (int i = front; i <= rear; i++) {
cout << arr[i] << " "; // Display all elements in the queue
}
cout << endl;
}
};

int main() {
cout << "Initialize three Queues." << endl;
Queue q1, q2, q3; // Creating instances of Queue
q1.enqueue(1);
q1.enqueue(2);
q1.enqueue(3);
q2.enqueue(1);
q2.enqueue(2);
q2.enqueue(3);
q3.enqueue(3);
q3.enqueue(2);
q3.enqueue(1);
cout << "Queue-1" << endl;
q1.display(); // Display elements of Queue-1
cout << "Queue-2" << endl;
q2.display(); // Display elements of Queue-2
cout << "Queue-3" << endl;
q3.display(); // Display elements of Queue-3
cout << "\nCheck if Queue-1 and Queue-2 are equal? " << q1.isEqual(q1, q2) << endl;
cout << "\nCheck if Queue-2 and Queue-3 are equal? " << q1.isEqual(q2, q3) << endl;
cout << "\nCheck if Queue-1 and Queue-3 are equal? " << q1.isEqual(q1, q3) << endl;
return 0;
}
```
```

Sample Output:

```Initialize three Queues.
Queue-1
Queue elements are: 1 2 3
Queue-2
Queue elements are: 1 2 3
Queue-3
Queue elements are: 3 2 1

Cheque Queue-1 and Queue-2 are equal? 1

Cheque Queue-2 and Queue-3 are equal? 0

Cheque Queue-1 and Queue-3 are equal? 0
```

Flowchart:

CPP Code Editor:

Previous C++ Exercise: Find the position of an element in a queue.
Next C++ Exercise: Intersection of two queues.

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