fzu 2036 2036 Log Calculator JAVA 浮点数输出精度控制

http://acm.fzu.edu.cn/problem.php?pid=2036

a>b

a=log2(x) x=2^a

b=log2(y) y=2^b

log2(x+y)=b+log2(1+2^(a-b));

/*

* To change this template, choose Tools | Templates

* and open the template in the editor.

*/

/**

*

* @author acm

*/

import java.util.*;

import java.math.*;

public class Main {

/**

* @param args the command line arguments

*/

public static void main(String[] args) {

// TODO code application logic here

Scanner cin=new Scanner(System.in);

int ci=cin.nextInt();

int pl=1;

while((ci--)!=0){

BigDecimal a,b;

a=cin.nextBigDecimal();

b=cin.nextBigDecimal();

if(a.compareTo(b)<0){

BigDecimal t=a;

a=b;

b=t;

}

BigDecimal ans=b;

BigDecimal deta=a.subtract(b);

if(deta.compareTo(BigDecimal.valueOf(32))>0){

ans=ans.add(deta);

}else{

double p=deta.doubleValue();

double cnt=Math.pow(2.0, p);

double tmp=Math.log(1+cnt)/Math.log(2.0);

ans=ans.add(BigDecimal.valueOf(tmp));

}

System.out.print("Case "+(pl++)+": ");

System.out.println(ans.setScale(9, BigDecimal.ROUND_HALF_UP));//保留小数点后9位

}

}

}

/*

* double a=0.036*100;

DecimalFormat df=new DecimalFormat("0.000");

System.out.println(df.format(a));//保留小数点后3位

*/