Uva679【Dropping Balls】找规律java题解

一开始用java模拟下所有小球的下落过程，结果超时TAT，后来发现是我用了Arrays.fill初始化导致的。。后改用紫书上找到的规律，模拟最后一个小球的过程:
当l是奇数时，它是往左走的第(I+1)/2个小球，否则是往右走的第I/2个小球。最后还由于没删除前面的代码又超时一发。。import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.StreamTokenizer;
import java.util.Arrays;
import java.util.Scanner;

public class Main {
static int d,l,n;
public static void main(String[] args) throws IOException {
StreamTokenizer in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));
while(in.nextToken() != StreamTokenizer.TT_EOF){
n = (int)in.nval;
if(n == -1) break;
for(int i = 0; i<n; i++){
in.nextToken();
d = (int)in.nval;
in.nextToken();
l = (int)in.nval;;
solve();
}

}
}
private static void solve() {
int k = 1;
for(int i = 0; i<d-1; i++){
if(l%2 == 1){
k = 2*k;
l = (l+1)/2;
}
else {
k = 2*k+1;
l /= 2;
}
}
/*超时TAT
* int m = (1<<d)-1;//此处注意<<的优先级小于-,所以要加上括号！
for(int i = 0; i<l; i++){
k = 1;
while(true){
judge[k] = !judge[k];
k=judge[k]?2*k:2*k+1;
if(k>m) break;
}
}*/
System.out.println(k);
}

}