How to Create Deque of Unordered_Set in C++?

In C++, a deque (double-ended queue) is a container that allows insertion and removal of elements from both ends whereas an unordered set is a container that stores unique elements in no particular order. In this article, we will learn how to create a deque of unordered sets in C++ STL.

Example:

Input: 
myUSet1 = {1, 2, 3} 
myUSet2 = {4, 5, 6}

Output: 
Deque Elements: 
uSet1: 3 1 2 
uSet2: 6 4 5 

Creating Deque of Unordered_Set in C++

To create a std::deque of std::unordered_set, we can use the std::deque template class that takes the type of the elements as a template parameter. We can pass the type as an unordered_set of a given type.

Syntax to Declare Deque of Unordered Set

deque<unordered_set<Type>> myDeque;

C++ Program to Create Deque of Unordered_Set

The below program demonstrates how we can create a deque of unordered_sets in C++.

// C++ program to illustrate how to create a deque of
// unordered sets
#include <deque>
#include <iostream>
#include <unordered_set>
using namespace std;

int main()
{
    // Declaring a deque of unordered sets
    deque<unordered_set<int> > myDeque;

    // Creating some unordered sets
    unordered_set<int> set1 = { 1, 2, 3 };
    unordered_set<int> set2 = { 4, 5, 6 };

    // Pushing unordered sets into the deque
    myDeque.push_back(set1);
    myDeque.push_back(set2);

    // Checking if the deque is empty
    cout << "Deque Elements: " << endl;
    int count = 1;
    for (auto& ele : myDeque) {
        cout << "uSet" << count << ": ";
        for (auto i : ele) {
            cout << i << " ";
        }
        count++;
        cout << endl;
    }

    return 0;
}

Deque Elements: 
uSet1: 3 1 2 
uSet2: 6 4 5 

Time Complexity: O(N*M), where N is the number of sets and M is the average size of each set.
Auxilliary Space: O(N*M)