HDU 2438 Turn The corner (calculate geometry + three points)

Turn the corner Time limit:3000/1000 MS (java/others) Memory limit:32768/32768 K (java/others) Total Submission (s): 2059 Accepted Submission (s): 785
problem DescriptionMr West bought a new car! So he's travelling around the city.

One day he comes to a vertical corner. The street he is currently in have a width x, the street he wants to turn to have a width y. The car has a length l and a width d.

Can Mr West go across the corner?

 
InputEvery line have four real numbers, X, Y, L and W.
Proceed to the end of file.
 
OutputIf He can go across the corner, print "Yes". Print "No" otherwise.
 Sample Input

10 6 13.5 410 6 14.5 4

 Sample Output

Yesno

 Source Asia Harbin Regional Contest Online

Title Link: http://acm.hdu.edu.cn/showproblem.php?pid=2438

The main topic: is to give 4 parameters, ask the car can turn the corner

Topic Analysis: Push formula, use the angle to indicate the distance from the point perpendicular to the corner of the curve when turning, it is obvious that H is the function of convexity, the three-point angle, the maximum value, if the maximum value is less than Y can pass, h = (l * cos (a) + W * sin (a)-X) * (Tan (a) + W * COS (a))

#include <cstdio> #include <cmath>double const PI = ACOs ( -1.0);d ouble Const EPS = 1e-7;double x, y, L, W, S, h; Double cal (Double a) {    s = l * cos (a) + W * sin (a)-X;    return S * TAN (a) + w * cos (a); int main () {    double Le, RI, mid1, Mid2;    while (scanf ("%lf%lf%lf%lf", &x, &y, &l, &w)! = EOF)    {        le = 0.0;        RI = PI/2;        while (Fabs (ri-le) > EPS)        {            Mid1 = (le + ri)/2;            Mid2 = (Mid1 + ri)/2;            if (Cal (MID1) >= cal (MID2))                ri = Mid2;            else                 le = mid1;        }        if (Cal (MID1) <= y)            printf ("yes\n");        else             printf ("no\n");}    }

HDU 2438 Turn The corner (calculate geometry + three points)