Selection Sort - C++

#include <iostream>
#include <string>
#include <vector>
#include <cstdlib>

using namespace std;

void selectionsort(vector<char>& vec) {
    int n = vec.size();

    // start from first element till last
    for (int i = 0; i < n; i++) {

        int min_pos = i; // assume first element is the smallest

        for (int j = i + 1; j < n; j++) {
            // update position of min element if we find a smaller one
            if (vec[j] < vec[min_pos]) {
                min_pos = j;
            }
        }

        // if the minimun is not at position i, we must swap
        if (min_pos != i) {
            int tmp = vec[i];
            vec[i] = vec[min_pos];
            vec[min_pos] = tmp;
        }
    }
}

int main() {
    cout << "give me a string" << endl;
    string s; getline(cin, s);

    vector<char> vec(s.begin(), s.end());

    if (!vec.empty()) selectionsort(vec);

    string str(vec.begin(), vec.end());

    cout << str << endl;
    return 0;
}