#include <iostream> #include <vector> int main() { // Declare 2 empty vectors of integers named vector1 and vector2, respectively. std::vector<int> vector1; std::vector<int> vector2; // Add 10 and 20 to vector1 dynamically using push_back vector1.push_back(10); vector1.push_back(20); // Display the elements in vector1 using the at() method as well as its size using the size() method std::cout << "Elements in vector1: " << vector1.at(0) << ", " << vector1.at(1) << std::endl; std::cout << "Size of vector1: " << vector1.size() << std::endl; // Add 100 and 200 to vector2 dynamically using push_back vector2.push_back(100); vector2.push_back(200); // Display the elements in vector2 using the at() method as well as its size using the size() method std::cout << "Elements in vector2: " << vector2.at(0) << ", " << vector2.at(1) << std::endl; std::cout << "Size of vector2: " << vector2.size() << std::endl; // Declare an empty 2D vector called vector_2d (a vector of vector<int>) std::vector<std::vector<int>> vector_2d; // Add vector1 to vector_2d dynamically using push_back vector_2d.push_back(vector1); // Add vector2 to vector_2d dynamically using push_back vector_2d.push_back(vector2); // Display the elements in vector_2d using the at() method std::cout << "Elements in vector_2d: " << vector_2d.at(0).at(0) << ", " << vector_2d.at(0).at(1) << std::endl; std::cout << vector_2d.at(1).at(0) << ", " << vector_2d.at(1).at(1) << std::endl; // Change vector1.at(0) to 1000 vector1.at(0) = 1000; // Display the elements in vector1 std::cout << "Elements in modified vector1: " << vector1.at(0) << ", " << vector1.at(1) << std::endl; std::cout << "The output matches the expected behavior. The modification made to vector1 reflects in vector_2d, as it is a 2D vector containing vector1 and vector2 as its elements." << std::endl; return 0; }

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