Exponentiation POJ

Exponentiation

POJ - 1001

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 R ⁿ where R is a real number ( 0.0 < R < 99.999 ) and n is an integer such that 0 < n <= 25.

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 R^n. Leading zeros should be suppressed in the output. Insignificant trailing zeros must not be printed. Don't print the decimal point if the result is an integer.

Sample Input

95.123 120.4321 205.1234 156.7592  998.999 101.0100 12

Sample Output

548815620517731830194541.899025343415715973535967221869852721.0000000514855464107695612199451127676715483848176020072635120383542976301346240143992025569.92857370126648804114665499331870370751166629547672049395302429448126.76412102161816443020690903717327667290429072743629540498.1075960194566517745610440100011.126825030131969720661201

Hint

If you don't know how to determine wheather encounted the end of input:
s is a string and n is an integer

C++while(cin>>s>>n){...}cwhile(scanf("%s%d",s,&n)==2) //to  see if the scanf read in as many items as you want/*while(scanf(%s%d",s,&n)!=EOF) //this also work    */{...}

如果使用java一下几点注意

scanf（……）！=EOF在java中可以用 while(scan.hasNext())

根据题目要求可以直接使用 java.math.BigDecimal.stripTrailingZeros() 返回一个BigDecimal，它在数值上等于这一个，但表示形式移除所有尾部零。

java.math.BigDecimal.toPlainString() 返回此BigDecimal的字符串表示形式不带指数字段。为具有正的精度值，中位数的小数点右边的数字用于指示精度。

String.StartsWith 方法

确定此字符串实例的开头是否与指定的字符串匹配。

String.substring方法

str＝str.substring(int beginIndex);截取掉str从首字母起长度为beginIndex的字符串，将剩余字符串赋值给str；

code：

import java.math.BigDecimal;import java.util.*;public class Main {public static void main(String[] args) {// TODO Auto-generated method stub        Scanner scan = new Scanner(System.in);        while(scan.hasNext()){        BigDecimal a = scan.nextBigDecimal();        int b = scan.nextInt();        String ans = a.pow(b).stripTrailingZeros().toPlainString();        if(ans.startsWith("0"))        ans = ans.substring(1);        System.out.println(ans);        }        scan.close();}}