here my code
#include<stdio.h>
#include<math.h>
#define R  1.3660254037844
#define R2 2.7320508075689
#define PI 3.1415926535898
#define H  2.3660254037844

double xShift[] = {R2, R, -R, -R2, -R, R };
double yShift[] = {0, H, H, 0, -H, -H};

double dist(double x1, double y1, double x2, double y2){
    x2 -= x1 ;
    y2 -= y1 ;
    return sqrt(x2*x2 + y2*y2);
}
double calc(double xUse, double yUse){
    int i,j,k;
    double x, y, L, RadiusI, alpha;
    double mL = 1000;//dist( 0, 0, xUse+R, yUse);
    for (k = 0; k<6;k++){
            L = dist(xUse, yUse, xShift[k]/2.0, yShift[k]/2.0);
            mL = (mL<L)?mL:L;
    }

    for (i = 1; i<10;i++){
        RadiusI = R2*i;
        alpha = PI/3.0/i;
        for (j = 0; j<6*i;j++){
            x = RadiusI * cos(alpha * j ) ;
            y = RadiusI * sin(alpha * j ) ;

            for (k = 0;k<6;k++){
                L = dist(xUse, yUse, xShift[k]/2.0 + x, yShift[k]/2.0+y);
                mL = (mL<L)?mL:L;
            }
        }
    }
    return mL;
}
int main(){

    double xCenter , yCenter;
    scanf("%lf",&xCenter);
    scanf("%lf",&yCenter);

    xCenter = fabs(xCenter);
    yCenter = fabs(yCenter);

    double L1 = calc(xCenter - R, yCenter);
    double L2 = calc(yCenter - R, xCenter);
    double minL = (L1 < L2)?L1:L2;
    minL = fabs(minL);


    printf("%.4lf",minL);

    return 0;
}