Courses
Tutorials
Practice
Contests

C++ Deque

This quiz tests your knowledge of C++ Deque container and its associated operations. It contains 10 MCQs.

Last Updated :

Discuss

Comments

Question 1

Add the missing code to get the given ouptut

C++

#include <bits/stdc++.h>
using namespace std;
int main()
{
    deque<int> dq = {1, 2, 3};

    // Missing code here

    for (int i : dq)
        cout << i << " ";
    return 0;
}

dq[1] = 23
dq.insert(dq.begin() + 1, 23);
dq.insert(dq.begin()++, 23);
dq.insert(1, 23);

Discuss it

Question 2

What will be the output of the following program?

C++

#include <bits/stdc++.h>
using namespace std;
void specialInsert(deque<int> &dq, int val)
{
    if (dq.size() == 0)
        dq.push_back(val);
    else if (val > dq.back())
        dq.push_back(val);
    else if (val < dq.front())
        dq.push_front(val);
    else
    {
        dq.insert(dq.end() - 1, val);
    }
}
int main()
{
    deque<int> dq;
    specialInsert(dq, 1);
    specialInsert(dq, 9);
    specialInsert(dq, 7);
    specialInsert(dq, 2);
    cout << dq.front() << endl;
    cout << dq.back();
    return 0;
}

Discuss it

Question 3

How does C++ STL deque achieve O(1) insertions, deletions, and random access?

Circular array with dynamic resizing
Linked list for insertions and deletions
Array of pointers to fixed-size blocks
Single dynamic array with resizing

Discuss it

Question 4

Match the deque operation with time complexity:

I. Insert at Beginning i) O(n)

II. Delete from Middle ii) O(1)

III. Find iii) O(n)

IV. Random Index Access iv) O(1)

I-ii, II-i, III-iv, IV-iii
I-ii, II-iii, III-i, IV-iv
I-i, II-iii, III-n, IV-ii
I-i, II-i, III-i, IV-i

Discuss it

Question 5

What is the time complexity of push_front() operation in a C++ deque?

O(1)
O(n log n)
O(n)
O(log n)

Discuss it

Question 6

How to find the size of the deque?

Using size()
Using length()
Using getSize()
Must be counted using loop

Discuss it

Question 7

Which of the following operations is not supported by deques in C++?

Insertion at both ends
Deletion at both ends
Accessing elements at any index
Sorting the elements

Discuss it

Question 8

Which of the following operations on a deque has O(n) time complexity?

insert()
push_front()
pop_back()
erase()

Discuss it

Question 9

How do you create a deque of strings?

deque<string> dq;
deque<char[]> dq;
deque char* dq;
string deque dq

Discuss it

Question 10

What will be the output of the following C++ code?

C++

#include <bits/stdc++.h>
using namespace std;
int main()
{
    deque<int> dq = {1, 2, 3};
    dq.push_back(4);
    dq.push_front(0);
    dq.pop_back();
    dq.pop_front();
    for (int i : dq)
        cout << i << " ";
    return 0;
}

0 1 2
2
1 2 3
1 2

Discuss it

Tags:

C++

There are 10 questions to complete.

Take a part in the ongoing discussion