题解 | #学英语#

分不同的函数处理：

1.处理个位和十位

2.处理百位

import javax.print.attribute.standard.RequestingUserName;
import java.util.Scanner;

public class Main {
    static String[] oneToNineteen = {"", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine","ten","eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eighteen", "nineteen"};
    static String[] twentyToNinety = {"","","twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninety"};

    static String[] threeUnit = {" ","thousand ","million ","billion "};


    public static String oneAndTen(int num) {
        if(num==0) return "";
        if (num <= 19) return oneToNineteen[num] +" ";
        return twentyToNinety[num/10] + (num%10==0?"":" ") + oneToNineteen[num%10] +" ";
    }

    public static String hundred(int num, int partOneTenPlace) {
        StringBuffer sb = new StringBuffer();
        int partHundredPlace = num % 10;
        if(partHundredPlace!=0){
            sb.append(oneToNineteen[partHundredPlace]).append(" hundred ");
            if(partOneTenPlace!=0){
                sb.append("and ");
            }
        }
        return sb.toString();
    }


    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        long number = in.nextLong();

        StringBuffer sb = new StringBuffer();

        int threeUnitIdx = 0;
        while(number>0){
            int partOneTenPlace = (int) (number % 100);
            String partOneAndTen = oneAndTen(partOneTenPlace);
            String partHundred = hundred((int) (number /= 100), partOneTenPlace);
            String partThreeUnit = threeUnit[threeUnitIdx++];
            sb.insert(0,partThreeUnit).insert(0,partOneAndTen).insert(0,partHundred);
            number /= 10;

        }

        System.out.println(sb);

    }
}