首页 > ACM题库 > HDU-杭电 > HDU 1063 Exponentiation-高精度-[解题报告] java
2013
11-26

HDU 1063 Exponentiation-高精度-[解题报告] java

Exponentiation

问题描述 :

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

import java.io.*;
import java.util.*;
import java.math.*;
public class Main{
	public static void main(String[] args){
		Scanner cin = new Scanner(System.in);
		while(cin.hasNextBigDecimal()){
			BigDecimal num = cin.nextBigDecimal();
			int n = cin.nextInt();
			num = num.pow(n);
			String r = num.stripTrailingZeros().toPlainString();    
			if(r.startsWith("0.")){
				r = r.substring(1);
			}
			System.out.println(r);
		}
	}
}

java中高精度就是好用啊!以后得多学一下。虽然程序的效率差,但是写起代码简单。

num.pow(int n)方法的功能是计算一个数的幂;

num.stripTrailingZeros()方法的功能是返回不大于此数但是除去尾部0的数值。

num.toPlainString()方法的功能是转换为相应的字符串。

方法的类型为 BigDecimal;

一个感觉,java中的高精度就是很简单,很好用。


  1. 可以根据二叉排序树的定义进行严格的排序树创建和后序遍历操作。如果形成的排序树相同,其树的前、中、后序遍历是相同的,但在此处不能使用中序遍历,因为,中序遍历的结果就是排序的结果。经在九度测试,运行时间90ms,比楼主的要快。