#include<stdio.h>
#include<math.h>
#include<stdlib.h>
#define N 8
#define A -1.0
#define B 5.0
double REALANS = 42.0;
double f(double x) {
    return x*(x - 1)*(x - 2)*(x - 3)*(x - 4) + 7;
}

int main() {
    double e = 1, h;
    int n = 1;
    while (e > 0.00001) {
        h = 6.0 / (N*n);
        double *x = (double*)malloc(sizeof(double)*N*n);
        double *y = (double*)malloc(sizeof(double)*N*n);
        for (int i = 0; i < n*N; i++) {
            x[i] = -1 + h*i;
            y[i] = f(x[i]);
        }
        double ans = 0;
        for (int i = 0; i < n*N; i++) {
            if (i == 0 || i == n*N - 1) {
                ans += y[i];
            }
            else {
                ans += y[i] * 2;
            }

        }
        ans *= h / 2;
        e = fabs(REALANS - ans);
        printf("ans = %.6f e=%.6f N=%d\n", ans, e, n*N);
        n = n * 2;
        free(x);
        free(y);
    }
    printf("------end------\n");
    getchar();
    return 0;
}