Question

The requirements (simplified) are ...

Using STL containers std::list, std::vector, and std::deque,

demonstrate the sorting of integers in descending order.

1. Use std::set to create a data set of unique integers.
2. Copy the data set to the other containers.
3. Shuffle the containers.
4. Display each container's contents.
5. Use appropriate sorting algorithms to sort the data in each container.
6. Redisplay each container's contents.

Code must be written in C++

Answer 1

Let us first discuss about each of these containers and their benefits before diving into examples for them :-

1. std::list - it is a container to store data in non contiguous manner, it is implemented using a doubly linked list and is faster compared to arrays in insertion and deletion operations

2. std::vector - It is a sequence container that enables dynamic size arrays,it can automatically expand / reduce on insertion or deletion respectively. It stores the data in contiguous memory spaces and can be accessed both via an iteration or a pointer to elements. Any new insertion happens in the end of the vector.

3.std::deque - They are called doubly ended queues and implemented on a data structure of the same name, they may or may not store data in contiguous memory and insertion and deletion are possible from both ends, it resembles a real life queue where insertion happens in the end and deletion happens in the front.

4. std::set is an associative container of unique objects of type Key that contains a sorted set .

Now coming to the given program :

#include <iostream>
#include <set>
#include <iterator>
#include <deque>
#include <list>
#include <bits/stdc++.h>

using namespace std;

int main()
{

   /*

step 1 - create a set of unique integers using std::set

*/
   set <int, greater <int> > set1;      

   // insert data into the set
   set1.insert(4);
   set1.insert(5);
   set1.insert(3);
   set1.insert(6);
   set1.insert(2);
   set1.insert(5); // only one 5 will be added
   set1.insert(1);

    // check if data is entered correctly
   set <int, greater <int> > :: iterator itr;
   cout << "\nThe initial set is : ";
   for (itr = set1.begin(); itr != set1.end(); ++itr)
   {
       cout << '\t' << *itr;
   }
   cout << endl;

/*
Declare the right representation of list , vector and deque to copy all values from the set
using a for loop and interating through the set
*/

deque <int> deque_ex1; // include the header on top
list<int> list_ex1; // include header on top
vector<int> vec_ex1; // include header on top

// iterators to above mentioned data structures not needed as they can add elements using push_back

   // assigning the elements to the list, dequeue and the vector

for (itr = set1.begin(); itr != set1.end(); ++itr)
   {
       // loop thorugh all elements of set
       //add to vector
       vec_ex1.push_back(*itr);
      
       //add to deque
        deque_ex1.push_back(*itr);
      
        //add to list
        list_ex1.push_back(*itr);
   }

    //shuffling elements
     // using built-in random generator:
     //1. for vector ;
      std::random_shuffle ( vec_ex1.begin(), vec_ex1.end() );
     //2. for deque
      std::random_shuffle ( deque_ex1.begin(), deque_ex1.end() );
     //3 for list
      //since the shuffle function does not work directly for lists it has to be converted to a vector and then shuffled , that needs to be copied back to the list
       vector<int> V( list_ex1.begin(), list_ex1.end() ); // copy list to vector
       std::random_shuffle( V.begin(), V.end()); //shuffle the vector
       list_ex1.assign( V.begin(), V.end() ); // copy back to list
  
    /*Displaying contents*/
    // For vector
    vector <int> :: iterator itr1;
    cout << "The shuffled vector is:";
    for (itr1 = vec_ex1.begin(); itr1 != vec_ex1.end(); ++itr1)
   {
       // loop thorugh all elements of set
       //add to vector
       cout << '\t' << *itr1;
   }
    cout<<endl;
  
// For deque
    deque <int> :: iterator itr2;
    cout << "The shuffled deque is:";
    for (itr2 = deque_ex1.begin(); itr2 != deque_ex1.end(); ++itr2)
   {
       // loop thorugh all elements of set
       //add to vector
       cout << '\t' << *itr2;
   }
    cout<<endl;

// For list
    list <int> :: iterator itr3;
    cout << "The shuffled list is:";
    for (itr3 = list_ex1.begin(); itr3 != list_ex1.end(); ++itr3)
   {
       // loop thorugh all elements of set
       //add to vector
       cout << '\t' << *itr3;
   }
    cout<<endl;
    cout<<endl;
  
    //sorting the data structures
    cout<<"Sorted data structures (using system defined sort function):"<<endl;
  
    sort (vec_ex1.begin(), vec_ex1.end());
    cout << "The sorted vector is:";
    for (itr1 = vec_ex1.begin(); itr1 != vec_ex1.end(); ++itr1)
   {
       // loop thorugh all elements of set
       //add to vector
       cout << '\t' << *itr1;
   }
    cout<<endl;
  
// For deque
    sort (deque_ex1.begin(), deque_ex1.end());
    cout << "The sorted deque is:";
    for (itr2 = deque_ex1.begin(); itr2 != deque_ex1.end(); ++itr2)
   {
       // loop thorugh all elements of set
       //add to vector
       cout << '\t' << *itr2;
   }
    cout<<endl;

// For list
    list_ex1.sort();
    cout << "The sorted list is:";
    for (itr3 = list_ex1.begin(); itr3 != list_ex1.end(); ++itr3)
   {
       // loop thorugh all elements of set
       //add to vector
       cout << '\t' << *itr3;
   }
    cout<<endl;
  
   return 0;

}

output