a fast standard deviation + mean calculator for my physics labs

physics-lab-stuff.cpp

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

void setIO(string name = "") {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    if (!name.empty()) {
        freopen((name + ".in").c_str(), "r", stdin);
        freopen((name + ".out").c_str(), "w", stdout);
    }
}

int main() {
    setIO("f");

    vector<double> values;
    double val;
    while (cin >> val) {
        values.push_back(val);
    }

    if (values.empty())
        return 0;

    double sum = 0;
    for (double x : values) {
        sum += x;
    }
    double mean = sum / values.size();

    double sq_sum = 0;
    for (double x : values) {
        sq_sum += (x - mean) * (x - mean);
    }
    double std_dev = sqrt(sq_sum / values.size());

    cout << "Average: " << mean << "\n";
    cout << "Standard Deviation: " << std_dev << "\n";
}