Challenge 1: A std::vector<int> With Five Pushed Values — Possible Solution
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#include <iostream>
#include <vector>

int main() {
    std::vector<int> nums;
    nums.push_back(10);
    nums.push_back(20);
    nums.push_back(30);
    nums.push_back(40);
    nums.push_back(50);

    for (int i = 0; i < nums.size(); i++) {
        std::cout << nums[i] << std::endl;
    }

    return 0;
}

Output:

    10
    20
    30
    40
    50

WHY THIS WORKS AS AN ANSWER
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Five push_back calls grow the vector one element at a time, with no
manual malloc/free anywhere in this code -- the vector manages its own
memory internally via RAII, exactly as the chapter describes. The
indexed loop uses nums.size() (an O(1) call, unlike c1-8's own O(n)
strlen) as the bound and operator[] to access each element in order.