UVALive 6135 Environment Protection (Simpson)

#include <iostream>
#include <cstdio>
#include <cmath>
using namespace std;
const double eps = 1e-10;
double w , h , area , a[4][10];
int k;
double function (double x , double *p , double *q , double y) {
    double up = 0 , down = 0;
    for (int i = 0 ; i <= k ; i ++) {
        up = up * x + p[i];
        down = down * x + q[i];
    }
    return max (y , up / down);
}
double simpson_formula (double l , double r , double *p , double *q , double y) {
    return (function (l , p , q , y) + 4 * function ((l + r) / 2.0 , p , q , y) + function (r , p , q , y)) * (r - l) / 6.0;
}
double simpson (double l , double r , double *p , double *q , double y) {
    double m = (l + r) / 2.0;
    double ans = simpson_formula (l , r , p , q , y);
    if (fabs (ans - simpson_formula (l , m , p , q , y) - simpson_formula (m , r , p , q , y)) < eps) return ans;
    return simpson (l , m , p , q , y) + simpson (m , r , p , q , y);
}
double gao (double low , double high) {
    double mid , ans = -1;
    int t = 50;
    while (t --) {
        mid = (low + high) / 2.0;
        double now = simpson (0 , w , a[0] , a[1] , mid) - simpson (0 , w , a[2] , a[3] , mid);
        if (now > area) ans = mid , low = mid;
        else high = mid;
    }
    return ans;
}
int main () {
    #ifndef ONLINE_JUDGE
        freopen ("input.txt" , "r" , stdin);
        // freopen ("output.txt" , "w" , stdout);
    #endif
    while (scanf ("%lf %lf %lf %d" , &w , &h , &area , &k) != EOF) {
        for (int i = 0 ; i < 4 ; i ++)
            for (int j = k ; j >= 0 ; j --) {
                scanf ("%lf" , &a[i][j]);
            }
        printf ("%.5f\n" , -gao (-h , 0));
    }
    return 0;
}