C++ Set and Multiset

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Question 1

What is the output of the following code?

#include <iostream>
#include <set>

int main() {
  std::multiset<int> s {1, 2, 3, 3, 3, 4, 4, 5};
  std::cout << s.count(3) << std::endl;
  return 0;
}

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Question 2

What is the output of the following code?

#include <iostream>
#include <set>

int main() {
  std::multiset<int> s {1, 2, 3, 3, 3, 4, 4, 5};
  s.erase(3);
  for (auto it = s.begin(); it != s.end(); ++it) {
    std::cout << *it << " ";
  }
  std::cout << std::endl;
  return 0;
}

1 2 3 4 5
1 2 4 4 5
1 2 4 5
2 4 5

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Question 3

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

#include <bits/stdc++.h>
using namespace std;
int main()
{
multiset<int> s;

s.insert(10);
s.insert(15);
s.insert(13);

for (auto it = s.begin(); it != s.end(); it++)
 cout << *it << " ";
cout<<endl;
// when 10 is present
auto it = s.upper_bound(10);
cout << (*it) << endl;
return 0;
}

10 13 15
13
10 15 13
13
13 15 10
15
15 13 10
10

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Question 4

What is the time complexity of clearing all elements from a multiset in the STL?

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

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Question 5

Which of the following statements about the multiset container class in the STL is NOT true?

A multiset is an ordered container that can store duplicate elements.
A multiset has fast element insertion and search times.
A multiset does not allow element modification or removal.
A multiset has constant time complexity for element access.

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Question 6

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

#include <bits/stdc++.h>
using namespace std;
int main()
{
int arr[] = { 14, 12, 15, 11, 10 };

set<int> s(arr, arr + 5);
for (auto it = s.cbegin(); it != s.cend(); it++)
 cout << *it << " ";
return 0;
}

10 11 12 14 15
12 14 15
15 14 13 12 11
13 12 11

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Question 7

What is the return type of the find() member function of the set container class in the STL?

int
bool
iterator
const_iterator

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Question 8

What is the main difference between a set and a vector in the STL?

A set is an ordered container, while a vector is an unordered container.
A set stores only unique elements, while a vector can store duplicate elements.
A set has constant time complexity for element insertion, while a vector has linear time complexity.
A set has constant time complexity for element access, while a vector has linear time complexity.

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Question 9

Which of the following statements about the set container class in the STL is NOT true?

A set is an ordered container that stores only unique elements.
A set has fast element insertion and search times.
A set is implemented as a binary search tree.
A set does not allow element modification or removal.

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Question 10

What is the time complexity of searching for an element in a set in the STL?

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

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C++

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