题解 | #学英语#

import java.util.*;

public class Main{
    public static HashMap<Integer,String> gwMap = new HashMap<Integer,String>();
    public static HashMap<Integer,String> swMap = new HashMap<Integer,String>();
    static{
    gwMap.put(1,"one");
    gwMap.put(2,"two");
    gwMap.put(3,"three");
    gwMap.put(4,"four");
    gwMap.put(5,"five");
    gwMap.put(6,"six");
    gwMap.put(7,"seven");
    gwMap.put(8,"eight");
    gwMap.put(9,"nine");
    gwMap.put(10,"ten");
    gwMap.put(11,"eleven");
    gwMap.put(12,"twelve");
    gwMap.put(13,"thirteen");
    gwMap.put(14,"fourteen");
    gwMap.put(15,"fifteen");
    gwMap.put(16,"sixteen");
    gwMap.put(17,"seventeen");
    gwMap.put(18,"eighteen");
    gwMap.put(19,"nineteen");
    swMap.put(2,"twenty");
    swMap.put(3,"thirty");
    swMap.put(4,"forty");
    swMap.put(5,"fifty");
    swMap.put(6,"sixty");
    swMap.put(7,"seventy");
    swMap.put(8,"eighty");
    swMap.put(9,"ninety");
    }
    
        
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        long num = sc.nextInt();
        StringBuilder sb = new StringBuilder();
        while(num>=1000){
            if(num/1000000000 == 0){
                num%= 1000000000;
                if(num/1000000 == 0){
                    num%= 1000000;
                    if(num/1000 == 0){
                        num%= 1000;
                    }else{
                        sb.append(ChineseToEnglish((int)(num/1000)));
                        sb.append("thousand ");
                        num%= 1000;
                    }
                }else{
                    sb.append(ChineseToEnglish((int)(num/1000000)));
                    sb.append("million ");
                    num%= 1000000;
                }
            }else{
                sb.append(ChineseToEnglish((int)(num/1000000000)));
                sb.append("billion ");
                num%= 1000000000;
            }
            
        }
        sb.append(ChineseToEnglish((int)num));
        System.out.println(sb.toString());
    }
    
    private static String ChineseToEnglish(int num){
        if(num<=0 || num >= 1000){
            return "";
        }
        
        StringBuilder sb = new StringBuilder();
        
        int bw = num/100;
        if(bw > 0){
            sb.append(gwMap.get(bw)+" ");
            sb.append("hundred ");
            if(num>100){
                sb.append("and ");
            }
        }
        num%= 100;
        int sw = num/10;
        if(sw > 1){
            sb.append(swMap.get(sw)+" ");
        }
        if(num>=10&&num<20){
            sb.append(gwMap.get(num)+" ");
        }else{
            int gw = num%10;
        if(gw > 0){
            sb.append(gwMap.get(gw)+" ");
        }
        }
        
        return sb.toString();
        
    }
}