Quick Sort

Probably the easiest understandable quick sort and quick select so far. ... I like this code!.

#include <vector>
#include <iostream>
using namespace std;


int qSelect(vector<int>& nums, int first, int last) {
    int pivot = nums[first];
    int p = first;   // use two pointer. P always points to be one less than pivot.
    for(int i = first + 1;  i <= last; ++i) {
        if(nums[i] < pivot) {
            p++;
            swap(nums[i], nums[p]);
        }
    }
    swap(nums[p], nums[first]);
    return p;
}

void qSort(vector<int>& nums, int first, int last) {
    int pivotIndex;
    if(first < last) {
        pivotIndex = qSelect(nums, first, last);
        qSort(nums, first, pivotIndex - 1);
        qSort(nums, pivotIndex + 1, last);
    }
}

void qSort(vector<int>& nums) {
    qSort(nums, 0, nums.size() - 1);
}

int main(void) {
    vector<int> nums{7, -13, 1, 3, 10, 5, 2, 4};
    qSort(nums, 0, 7);
    for(int i = 0; i < nums.size(); ++i) {
        cout << nums[i] << endl;
    }
}