Embercode: AI-powered software engineer course

1. What does this program print? ``

cpp
#include <cstddef>
#include <iostream>
#include <vector>

int main() {
    std::vector<int> values = {10, 20, 30, 40};
    std::size_t hole = 1;
    values[hole] = values.back();
    values.pop_back();
    for (int v : values) std::cout << v << ' ';
    std::cout << '\n';
}

``

10 20 30 4040 20 3010 40 3010 30 40

2. What does this program print? ``

cpp
#include <cstddef>
#include <iostream>
#include <vector>

int main() {
    std::vector<int> values = {10, 20, 30};
    std::size_t hole = 2;
    values[hole] = values.back();
    values.pop_back();
    std::cout << "size " << values.size() << '\n';
    for (int v : values) std::cout << v << ' ';
    std::cout << '\n';
}

``

size 2; 10 20size 3; 10 20 30size 2; 10 30size 1; 10

3. Which statements about the RandomSet from this lesson are true? Select all that apply.

Pick every answer that is true.

Inserting a value that is already in the set returns false and changes nothingRemoving a value shifts every later value one place left to fill the gapRemoving a value moves the last value into the removed value's slotrandom_pick draws one random index and reads one element of the vectorA hash map can return the key at position 7 in O(1), so the vector is not needed

4. Which statements about the steps of remove are true? Select all that apply.

Pick every answer that is true.

remove looks the value up in the map before it changes anythingIf the removed value is the last item, erasing its key before the moved value is written back puts the removed value into the map againremove shifts the later values left, so the map needs no updateremove returns false and changes nothing when the value is not in the map

5. Why can remove avoid shifting values to fill the gap?

A hash map keeps the values in sorted order, so the gap is easy to findRemoved values are marked and skipped on the next random pickThe vector copies itself into a bigger block on every removeThe vector has no required order, so moving one value into the gap is enough

O(1) random set