C++ Queue Exercises: Find the mode of all elements of a queue

C++ Queue: Exercise-7 with Solution

Write a C++ program to find the mode of all elements of a queue.

Sample Solution:

C Code:

#include <iostream>
#include <map> // Include map library for using map data structure

using namespace std;

const int MAX_SIZE = 100;

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

  public:
    Queue() {
      front = -1; // Initialize front index to -1
      rear = -1; // Initialize 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 message if queue is full
        return;
      }
      if (isEmpty()) {
        front = 0;
        rear = 0;
      } else {
        rear++;
      }
      arr[rear] = x; // Insert the element at the rear index
    }

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

    void display() {
      if (isEmpty()) {
        cout << "Error: Queue is empty" << endl; // Display error message if 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 find_Mode() {
      map < int, int > freq; // Map to store element frequency
      int mode = -1; // Initialize mode to -1
      int maxFreq = -1; // Initialize maximum frequency to -1
      for (int i = front; i <= rear; i++) {
        freq[arr[i]]++; // Increment frequency count for each element in the queue
        if (freq[arr[i]] > maxFreq) {
          maxFreq = freq[arr[i]]; // Update maximum frequency
          mode = arr[i]; // Update mode to the element with maximum frequency
        }
      }
      return mode; // Return the mode of the elements in the queue
    }
};

int main() {
  cout << "Initialize a Queue." << endl;
  Queue q;
  cout << "\nInsert some elements into the queue:" << endl;
  q.enqueue(1);
  q.enqueue(2);
  q.enqueue(3);
  q.enqueue(4);
  q.enqueue(4);
  q.display();

  // Find and display the mode of elements in the queue
  int mode_val = q.find_Mode();
  cout << "Find the mode of all elements of the said queue: " << mode_val;

  cout << "\n\nInput one more element into the queue:" << endl;
  q.enqueue(3);
  q.enqueue(3);
  q.display();

  // Find and display the mode of elements in the queue after adding new elements
  mode_val = q.find_Mode();
  cout << "Find the mode of all elements of the said queue: " << mode_val;

  return 0;
}

Sample Output:

Initialize a Queue.

Insert some elements into the queue:
Queue elements are: 1 2 3 4 4 
Find the mode of all elements of the said queue: 4

Input one more element into the queue:
Queue elements are: 1 2 3 4 4 3 3 
Find the mode of all elements of the said queue: 3

Flowchart:

CPP Code Editor:

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Previous C++ Exercise: Find the median of all elements of the said queue.
Next C++ Exercise: Mean, variance and standard deviation of all elements of a queue.