hdu Turn the corner

Turn the corner

Time Limit: 3000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)

Total Submission(s): 336    Accepted Submission(s): 141

Problem Description

Mr. West bought a new car! So he is travelling around the city.
One day he comes to a vertical corner. The street he is currently in has a width x, the street he wants to turn to has a width y. The car has a length l and a width d.
Can Mr. West go across the corner?

 

Input

Every line has four real numbers, x, y, l and w. Proceed to the end of file.

 

Output

If he can go across the corner, print "yes". Print "no" otherwise.

 

Sample Input

10 6 13.5 4
10 6 14.5 4

 

Sample Output

yes
no

 

Source

2008 Asia Harbin Regional Contest Online

 

Recommend

gaojie

 

分析：三分+计算几何题。公式推导略，附三分最保险的写法。

#include<cstdio>
#include<cmath>
#define eps 1e-6
#define pi acos(-1)
double x, y, L, D;

double fun(double st) {
    return -x / tan(st) + L * cos(st) + D / sin(st);
}

int main() {
    double a, b, c, d, temp;
    while (scanf("%lf%lf%lf%lf", &x, &y, &L, &D) != EOF) {
        a = eps;
        b = pi / 2;
        while (b - a > eps) {
            temp = (b - a) / 3;
            c = a + temp;
            d = b - temp;
            if (fun(c) > fun(d))
                b = d;
            else
                a = c;
        }
        if (fun(a) <= y)
            printf("yes\n");
        else
            printf("no\n");
    }
    return 0;
}