Test: Hashmaps - 2 - Software Development MCQ

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

In case of a collision in a hashmap, which technique is commonly used to handle it?

What will be the output of the following code?
#include <iostream>
#include <unordered_map>

int main() {
    std::unordered_map<int, std::string> colors;
    colors[1] = "Red";
    colors[2] = "Green";
    colors[3] = "Blue";

    std::cout << colors[2];

    return 0;
}

What will be the output of the following code?
#include <iostream>
#include <unordered_map>

int main() {
    std::unordered_map<int, int> numbers;
    numbers[1] = 10;
    numbers[2] = 20;
    numbers[3] = 30;
    numbers[4] = 40;

    std::cout << numbers[5];

    return 0;
}

What will be the output of the following code?
#include <iostream>
#include <unordered_map>

int main() {
    std::unordered_map<std::string, int> ages;
    ages["John"] = 25;
    ages["Alice"] = 30;
    ages["Bob"] = 35;

    std::cout << ages["Alice"];

    return 0;
}

What will be the output of the following code?
#include <iostream>
#include <unordered_map>

int main() {
    std::unordered_map<char, int> frequencies;
    frequencies['a'] = 2;
    frequencies['b'] = 3;
    frequencies['c'] = 1;

    std::cout << frequencies['d'];

    return 0;
}

What will be the output of the following code?
#include <iostream>
#include <unordered_map>

int main() {
    std::unordered_map<int, std::string> colors;
    colors[1] = "Red";
    colors[2] = "Green";
    colors[3] = "Blue";

    std::unordered_map<int, std::string>::iterator it;
    for (it = colors.begin(); it != colors.end(); it++) {
        std::cout << it->second << " ";
    }

    return 0;
}

What is the time complexity of finding the maximum element in a hashmap?

Which of the following operations can be performed in O(1) time for a hashmap?

In a hashmap, how is the size of the underlying array typically chosen?

Which of the following is an advantage of using a hashmap over an array?

In C++, which header file is required to use the unordered_map class?