What will be the output of the following C++ code? C++ #include <algorithm> #include <iostream> #include <string> using namespace std; int main() { string str = "hello"; reverse(str.begin() + 1, str.end() - 2); cout << str << endl; return 0; }

The code will produce a compile-time error.

C++ STL Mutating Algorithms

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Question 1

Which of the following steps has the highest time complexity in the program for sorting elements based on frequency?

Sorting the frequency vector of pairs.
Reconstructing the array from the frequency vector.
Inserting elements into the result array.
Creating the frequency map using unordered_map.

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Question 2

What will be the output of the following program?

C++

#include <bits/stdc++.h>
using namespace std;
int main()
{
    vector<int> v = {1, 2, 3, 4, 5, 6};
    reverse(v.begin(), v.begin() + 2);
    reverse(v.begin() + 2, v.end());
    reverse(v.begin(), v.end());
    for (int i = 0; i < v.size(); i++)
        cout << v[i] << " ";
    return 0;
}

6 5 4 3 2 1
5 6 1 2 3 4
3 4 5 6 1 2
1 2 3 4 5 6

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Question 3

What is the time complexity of make_heap function in C++?

O(1)
O(n log n)
O(n^2)
O(n)

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Question 4

Which of the following is true about the merge() function in C++?

The input sequences must be sorted in ascending order for the merge to work correctly.
It can merge two unsorted sequences without sorting them first.
The merge function returns the merged sequence directly, not an iterator.
The merge() function always merges two sequences into the first sequence.

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Question 5

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

C++

#include <algorithm>
#include <iostream>
#include <string>

using namespace std;

int main()
{
    string str = "hello";
    reverse(str.begin() + 1, str.end() - 2);
    cout << str << endl;
    return 0;
}

hello
hlelo
olleh
The code will produce a compile-time error.

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Question 6

Which of the following describes the internal working of prev_permutation() in C++?

It finds the first increasing element, swaps it with the largest smaller element.
It finds the first non-increasing element, swaps it with the largest smaller element, and reverses the right subsequence.
It sorts in descending order and returns the next smaller permutation.
It finds the first decreasing element, swaps it with the smallest greater element, and returns the next permutation.

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Question 7

What will be the output of the given program?

C++

#include <bits/stdc++.h>
using namespace std;
struct Point
{
    int x, y;
    bool operator<(Point &oth)
    {
        return this->y > oth.y;
    }
};
int main()
{
    Point arr[] = {{3, 10}, {2, 8}, {5, 4}};
    int n = sizeof(arr) / sizeof(arr[0]);
    sort(arr, arr + n);
    for (auto i : arr)
    {
        cout << i.x << " " << i.y << endl;
    }
    return 0;
}

5 4
2 8
3 10
3 10
2 8
5 4
2 8
3 10
5 4
3 10
5 4
2 8

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Question 8

Complete the myCmp() function in the program to sort the array arr in descending order based in the y coordinate.

C++

#include <bits/stdc++.h>
using namespace std;
struct Point
{
    int x, y;
};
bool myCmp(Point p1, Point p2)
{
    // Missing code here
}
int main()
{
    Point arr[] = {{3, 10}, {2, 8}, {5, 4}};
    int n = sizeof(arr) / sizeof(arr[0]);
    sort(arr, arr + n, myCmp);
    return 0;
}

return (p1.y > p2.y);
return (p1.x < p2.x);
return (p1.y < p2.y);
return (p1.x > p2.x);

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Question 9

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

C++

#include <bits/stdc++.h>
using namespace std;
int main()
{
    vector<int> v = {1, 2, 3};
    next_permutation(v.begin(), v.end());
    for (int i : v)
        cout << i << " ";
    return 0;
}

1 2 3
2 1 3
3 2 1
1 3 2

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Question 10

Which of the following data structures can be sorted using the sort() function in C++?

list<int>
set<int>
vector<int>
unordered_map<int, int>

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