华为-学英语

（java实现）

问题描述：

题目描述

Jessi初学英语，为了快速读出一串数字，编写程序将数字转换成英文：

如22：twenty two，123：one hundred and twenty three。
说明：
数字为正整数，长度不超过九位，不考虑小数，转化结果为英文小写；
输出格式为twenty two；
非法数据请返回“error”；
关键字提示：and，billion，million，thousand，hundred。
本题含有多组输入数据。

输入描述:

输入一个long型整数

输出描述:

输出相应的英文写法

示例1

输入

2356

输出

two thousand three hundred and fifty six

问题分析：

算法实现：

略

参考代码：

import java.util.*;
public class Main {
    //个位数
    public static String[] num1 = {"zero","one","two","three","four","five","six","seven","eight","nine"};
    //十位数
    public static String[] num2 = {"twenty","thirty","forty","fifty","sixty","seventy","eighty","ninety"};
    //11-19
    public static String[] num3 = {"ten","eleven","twelve","thirteen","fourteen","fifteen","sixteen","seventeen","eighteen","nineteen"};
    
    public static void main(String[] args)
    {
        Scanner input = new Scanner(System.in);
        while (input.hasNext())
        {
            long num = input.nextLong();
            System.out.println(parse(num));
        }
        input.close();
    }
    
    public static String parse(long num)
    {
        if (num<0)
            return "error";
        StringBuilder res = new StringBuilder();
        long billion = num/1000000000;    //处理亿万
        if (billion != 0)
        {
            res.append(trans(billion) + " billion ");
        }
        num %= 1000000000;
        long million = num/1000000;        //处理百万
        if (million != 0)
        {
            res.append(trans(million) + " million ");
        }
        num %= 1000000;
        long thousand = num/1000;        //处理千
        if (thousand != 0)
        {
            res.append(trans(thousand) + " thousand ");
        }
        num %= 1000;    //处理剩下1000
        if (num != 0)
        {
            res.append(trans(num));
        }
        return res.toString().trim();   //去掉尾部空格
    }
    
    public static String trans(long num)
    {
        StringBuilder res = new StringBuilder();
        long h = num/100;
        if(h != 0)
        {
            res.append(num1[(int)h] + " hundred ");
        }
        num %= 100;
        if (h != 0)
        {
            res.append("and ");    //百位不为0
        }
        if (num>=20)
        {
            //处理十位
            res.append(num2[(int)num/10-2]);
            //处理个位
            if (num%10 != 0)
            {
                res.append(" "+ num1[(int)num%10]);
            }
        }else if(num>=10 && num<20)
        {
            res.append(num3[(int)num-10]);
        }else
        {
            res.append(num1[(int)num]);
        }
        return res.toString().trim();   //去掉尾部空格
    }
}