POJ 1001: Exponentiation

题目描述

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 0 < n <= 25. 

输入

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.

输出

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.

样例输入

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

样例输出

548815620517731830194541.899025343415715973535967221869852721
.00000005148554641076956121994511276767154838481760200726351203835429763013462401
43992025569.928573701266488041146654993318703707511666295476720493953024
29448126.764121021618164430206909037173276672
90429072743629540498.107596019456651774561044010001
1.126825030131969720661201
分析：题目不是很友好，JAVA过的。

import java.math.*;
import java.util.*;

class Main {
    public static void main(String[] args) {
        Scanner cin=new Scanner(System.in);
        while(cin.hasNext()){
            BigDecimal r=cin.nextBigDecimal();
            int n=cin.nextInt();
            BigDecimal ans= r.pow(n);
            ans=ans.stripTrailingZeros();
            String astring=ans.toPlainString();
            if(astring.startsWith("0."))astring=astring.substring(1);
            System.out.println(astring);
        }
    }
}