2016 ---- Angry Birds

Topics requirements:

Planet X Angry Birds hit like a train! On a train between two flat tracks 1000 m apart. Two trains (referred wish A and B) at a speed of 10 m / sec with a relative. A car from angry birds starting speed of 50 m / sec, crashed car B, then return the car run into the A, B car run into the back, .... and so forth of the two trains stop at a distance of 1 meter.

Q: During this period hit Angry Birds B car How many times?

Note: You need to submit is an integer (B represents the number of hit car), do not fill anything else.

package org.bluebridge.topics;
public class Main { 

	static int i = 0; //次数的两倍
	static int time = 0;//碰撞B车的速度
	
    public static double dis(double length) { //两车相距的距离
    	double t = length / 60; 	    //第一次恰好碰撞的时间
    	length = length - 2 * t * 10; 	    //第一次碰撞时小鸟从A车走到B车后两车的距离
    	
    	//满足条件，返回结果
    	if (length <= 1) {
    		return 0;
    	}
    	//因为小鸟来回碰撞A和B车，题目只要求碰撞B车的次数，所以要除以2
    	if (i % 2 == 0) {
    		time++;
    	} 
    	i++;
    	return dis(length);//递归深搜
    }
	public static void main(String[] args) {
		dis(1000);//从最长距离1000逐渐减少两车之间的距离
		System.out.println(time); 
	}
}

The answer is: 9