大数 Java 幂 Exponentiation

Problem F: Exponentiation

Time Limit: 1 Sec  Memory Limit: 128 MB
Submit: 9  Solved: 6
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Description

Problems involving the computation of exact values of very large magnitude and precision are common. For example, the computation of the national debt is a taxing experience for many computer systems.

This problem requires that you write a program to compute the exact value of Rn where R is a real number ( 0.0 < R < 99.999) and n is an integer such that .

 

Input

The input will consist of a set of pairs of values for R and n. The R value will occupy columns 1 through 6, and the n value will be in columns 8 and 9.

 

Output

The output will consist of one line for each line of input giving the exact value of Rn. Leading zeros and insignificant trailing zeros should be suppressed in the output.

 

Sample Input

95.123 12
0.4321 20
5.1234 15
6.7592  9
98.999 10
1.0100 12

Sample Output

548815620517731830194541.899025343415715973535967221869852721
.00000005148554641076956121994511276767154838481760200726351203835429763013462401
43992025569.928573701266488041146654993318703707511666295476720493953024
29448126.764121021618164430206909037173276672
90429072743629540498.107596019456651774561044010001
1.126825030131969720661201

HINT

大数a的n次幂,直到读到EOF(文件结尾)为止,其中忽略小数后面的0

package sishuyan;
import java.math.BigDecimal;
import java.util.Scanner;
public class Bignum {
    public static void main(String[] args) {
        Scanner s=new Scanner(System.in); 
        BigDecimal a;
        int b;
        String c;
        while(s.hasNext()){
            a=s.nextBigDecimal();
            b=s.nextInt();;
            a=a.pow(b).stripTrailingZeros();//stripTrailingZeros将所得结果小数部分尾部的0去除
            c=a.toPlainString();//toPlainString将所得大数结果不以科学计数法显示,并转化为字符串
            if(c.charAt(0)=='0')//用charAt()判定首位字符是否为0
                c=c.substring(1);//substring()是截取字符串的一个方法，substring(index)从最开始也就是第一位截取，截取index位。
            System.out.println(c);
        }
    }
}