Całki

#include <iostream>
#include <cmath>

using namespace std;

double func(double x) {
    return sin(x);
}

double i(double x, double max, double n) {
    double tempx = x - 1;
    double sum = 0;
    for(int i = 0; i < n; ++i) {
        sum += func(tempx);
        tempx += 1;
    }

    tempx = x - 1;

    for(int i = 0; i < n; ++i) {
        tempx += 1;
        sum += func(tempx);
    }

    tempx = x;
    double xt = 0;

    for(int i = 0; i < n; ++i) {
        xt = (tempx + tempx + 1) / 2;
        sum += 4 * func(xt);
        ++tempx;
    }

    sum = sum * (max - x) / 6 / n;
    return sum;

}


int main() {
    double n;
    cin >> n;
    cout << i(0, 2*M_PI, n);
}