Quicksort in C++ three lines

quicksort.cpp

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

using namespace std;

void q(std::vector<int>::iterator b, std::vector<int>::iterator e) {
        auto d = std::partition(b, e, [&](int s) { return s <= *b; });
        if (b < e) q(b, d - 1), q(d, e);
}

void q2(std::vector<int>::iterator b, std::vector<int>::iterator e) {
        if (b >= e) { return; }
        std::vector<int> temp, temp2, temp3 { *b };
        std::copy_if(b + 1, e, std::back_inserter(temp), [&](int s) { return s < *b; });
        q(temp.begin(), temp.end());
        std::copy_if(b + 1, e, std::back_inserter(temp2), [&](int s) { return s >= *b; });
        q(temp2.begin(), temp2.end());
        std::copy(temp2.begin(), temp2.end(), std::copy(temp3.begin(), temp3.end(), std::copy(temp.begin(), temp.end(), b)));
}

int main()
{
    std::vector<int> x { 1, 3, 2, 5, 9, 1 };

    q(x.begin(), x.end());

    for (auto a: x) {
        std::cout << a << " - ";
    }
    return 0;
}