hdu1155 Bungee Jumping（物理题）

Bungee Jumping

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)

Total Submission(s): 1181    Accepted Submission(s): 507

Problem Description

Once again, James Bond is fleeing from some evil people who want to see him dead. Fortunately, he has left a bungee rope on a nearby highway bridge which he can use to escape from his enemies. His plan is to attach one end of the rope to the bridge, the other end of the rope to his body and jump off the bridge. At the moment he reaches the ground, he will cut the rope, jump into his car and be gone.

Unfortunately, he had not had enough time to calculate whether the bungee rope has the right length, so it is not clear at all what is going to happen when he jumps off the bridge. There are three possible scenarios:
The rope is too short (or too strong), and James Bond will never reach the ground.
The rope is too long (or too weak), and James Bond will be going too fast when he touches the ground. Even for a special agent, this can be very dangerous. You may assume that if he collides at a speed of more than 10 m/s, he will not survive the impact.
The rope's length and strength are good. James Bond touches the ground at a comfortable speed and can escape.
As his employer, you would like to know whether James Bond survives or whether you should place a job ad for the soon-to-be vacant position in the local newspaper. Your physicists claim that:
The force with which James is pulled towards the earth is
9.81 * w,
where w is his weight in kilograms and 9.81 is the Earth acceleration in meters over squared seconds.
Mr. Bond falls freely until the rope tautens. Then the force with which the bungee rope pulls him back into the sky depends on the current length of the rope and is
k * Δl,
where Δl is the difference between the rope's current length and its nominal, unexpanded length, and k is a rope-specific constant.
Given the rope's strength k, the nominal length of the rope l in meters, the height of the bridge s in meters, and James Bond's body weight w, you have to determine what is going to happen to our hero. For all your calculations, you may assume that James Bond is a point at the end of the rope and the rope has no mass. You may further assume that k, l, s, and w are non-negative and that s < 200.

The input contains several test cases, one test case per line. Each test case consists of four floating-point numbers (k, l, s, and w) that describe the situation. Depending on what is going to happen, your program must print "Stuck in the air.", "Killed by the impact.", or "James Bond survives.". Input is terminated by a line containing four 0s, this line should not be processed.

 

Sample Input

350 20 30 75375 20 30 75400 20 30 75425 20 30 75450 20 30 75400 20 30 50400 20 30 80400 20 30 850 0 0 0

 

Sample Output

Killed by the impact.James Bond survives. James Bond survives. James Bond survives. Stuck in the air.Stuck in the air.James Bond survives. Killed by the impact.

 

题意：詹姆斯邦德从高处跳下，身上绑了一根跳绳，给你下路高度，绳长，跳绳的劲度系数和詹姆斯的体重，让你求他是否能活下来，相当于物理题吧，只要不过简单点的，他只能在落地的时候剪短绳子（这个人脑子肯定有问题，不过这样问题就简单了）。

#include<cstdio>#include<cstring>#include<cmath>#include<algorithm>using namespace std;int main(){double f,l,s,w;while(scanf("%lf%lf%lf%lf",&f,&l,&s,&w)&&(f||l||s||w)){double sum,v=0;sum=w*9.81*s;if(s>l)  //如果绳子大于落地的高度，就直接算重力势能就行    sum-=f*(s-l)*(s-l)/2;if(sum<0){printf("Stuck in the air.\n");continue;}v=sqrt(sum*2/w);if(v>10)printf("Killed by the impact.\n"); else             printf("James Bond survives.\n");}return 0;}