Challenge 1: Sorting Descending With a Lambda Comparator — Possible Solution
====================================================================

#include <iostream>
#include <vector>
#include <algorithm>

int main() {
    std::vector<int> nums = {3, 7, 1, 9, 4};

    std::sort(nums.begin(), nums.end(), [](int a, int b) {
        return a > b;
    });

    for (int n : nums) {
        std::cout << n << std::endl;
    }

    return 0;
}

Output:

    9
    7
    4
    3
    1

WHY THIS WORKS AS AN ANSWER
------------------------------
The lambda [](int a, int b) { return a > b; } is passed directly as
std::sort's third argument, exactly the chapter's own pattern -- since
it returns true when a should come BEFORE b in "greater than" order,
std::sort produces a descending result instead of its default
ascending one, with no separate named comparator function needed.