HDU 1063/POJ 1001-Exponentiation（大数类）

Exponentiation

Time Limit: 1000/500 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)
Total Submission(s): 6948    Accepted Submission(s): 1967

Problem 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 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 12
0.4321 20
5.1234 15
6.7592  9
98.999 10
1.0100 12
一开始没考虑整数的情况WA一次。。
import java.io.*;
import java.util.*;
import java.math.*;
public class Main {
       public static void main(String[] args){
    	   Scanner in=new Scanner(System.in);
    	   BigDecimal a;int n,sta,end;
    	   while(in.hasNext()){
    		   int flag=1;
    		   a=in.nextBigDecimal();n=in.nextInt();
    		   String y=new String(a.toPlainString());
    		   for(int i=0;i<y.length();i++)
    			   if(y.charAt(i)=='.'){
    				   flag=0;
    				   break;
    			   }
    		   if(flag!=0){
    			   System.out.println(a.pow(n));
    			   continue;
    		   }
    		   a=a.pow(n);
    		   String x=new String(a.toPlainString());
    		   sta=0;end=x.length()-1;
    		   while(x.charAt(sta)=='0') sta++;
    		   while(x.charAt(end)=='0') end--;
    		   while(x.charAt(end)=='.') end--;
    		   for(int i=sta;i<=end;i++)
    			   System.out.print(x.charAt(i));
    		   System.out.println("");
    	   }
       }
}