easy c++ reverse

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


vector<string> vec;


void reverse(int dist)
{
    swap(vec[dist], vec[vec.size() - dist - 1]);
    if (dist != vec.size() / 2) reverse(dist + 1);
}


int main(int argc, char* argv[])
{
    int len = argc - 1;
    vec.resize(len);
    for (int i = 1; i <= len; ++i) {
        vec[i - 1] = string(argv[i]);
    }
    if (len > 0) reverse(0);
    else cerr << "Usage: " << argv[0] << " param1 [param2, param3, ...]" << endl;
    for (int i = 0; i < len; ++i) cout << vec[i] << " ";
    cout << endl;
    return 0;
}