给定一个整数，打印该整数的英文描述。
示例 1:
输入: 123
输出: “One Hundred Twenty Three”
示例 2:
输入: 12345
输出: “Twelve Thousand Three Hundred Forty Five”
示例 3:
输入: 1234567
输出: “One Million Two Hundred Thirty Four Thousand Five Hundred Sixty Seven”
示例 4:
输入: 1234567891
输出: “One Billion Two Hundred Thirty Four Million Five Hundred Sixty Seven Thousand Eight Hundred Ninety One”
java代码：
class Solution {
private static String[] UNITS={"Thousand","Million","Billion"};
private static String[] ONE={"One","Two","Three","Four","Five","Six","Seven","Eight","Nine", "Ten", "Eleven","Twelve","Thirteen","Fourteen","Fifteen","Sixteen","Seventeen","Eighteen","Nineteen"};
private static String[] TWO={"Twenty","Thirty","Forty","Fifty","Sixty","Seventy","Eighty","Ninety"};
public String numberToWords(int num) {
if(num==0) return "Zero";
String str="";int i=0;
while(num!=0){
String ret = getString(num%1000);
if(i!=0 && !ret.isEmpty()) ret+=" "+UNITS[i-1];
if(!ret.isEmpty() && !str.isEmpty()) ret+=" ";
str=ret+str;i++;num/=1000;
}
return str;
}
private String getString(int num){
String str="";int value = num%100;
if(value==0);
else if(value<20)str+=ONE[value-1];
else str+= TWO[value/10-2]+((value%10)==0? "":(" "+ONE[(value%10)-1]));
if(num>=100) str=ONE[num/100-1]+" "+"Hundred"+(str.isEmpty()?str:(" "+str));
return str;
}
}
