Q10310: Dog and Gopher

// Run time: 0.010
#include <stdio.h>

double gx, gy, dx, dy;
bool test(double arr[2]);
double distance(double x, double y, double arr[2]);
int main()
{
    int n;
    int i;

    while (scanf("%d", &n) != EOF)
    {
        double hole[n][2];
        scanf("%lf %lf %lf %lf", &gx, &gy, &dx, &dy);

        for ( i = 0; i < n; i++)
            scanf("%lf %lf", &hole[i][0], &hole[i][1]);

        for ( i = 0; i < n; i++)
            if (test(hole[i]))
                break;

        printf("The gopher ");
       
        if (i == n)
            printf("cannot escape.\n");
        else
            printf("can escape through the hole at (%.3lf,%.3lf).\n", hole[i][0], hole[i][1]);
    }

    return 0;
}

bool test(double arr[2])
{
    double d, g;
    d = distance(dx, dy, arr);
    g = distance(gx, gy, arr);

    // without sqrt, so we should use 4 times to compare.
    if (4*g  <= d)
        return true;
    else
        return false;

}

double distance(double x, double y, double arr[2])
{
    return (arr[0]-x)*(arr[0]-x)+(arr[1]-y)*(arr[1]-y);
}