Leetcode 273.整数转换英文表示

整数转换英文表示

将非负整数转换为其对应的英文表示。可以保证给定输入小于 2³¹ - 1 。

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"

class Solution {
    static String num1[]={"One","Two","Three","Four","Five","Six","Seven","Eight","Nine"};
    static String num2[]={"Ten","Eleven","Twelve","Thirteen","Fourteen","Fifteen","Sixteen","Seventeen","Eighteen","Nineteen"};
    static String tens[]={"Twenty","Thirty","Forty","Fifty","Sixty","Seventy","Eighty","Ninety"};
    public String numberToWords(int num) {
        if(num==0){
            return "Zero";
        }
        String result="";
        if(num>999999999){
            result+=numberToWordsWithThreeDIgit(num/1000000000)+" Billion";
            num%=1000000000;
        }
        if(num>999999){
            result+=numberToWordsWithThreeDIgit(num/1000000)+" Million";
            num%=1000000;
        }
        if(num>999){
            result+=numberToWordsWithThreeDIgit(num/1000)+" Thousand";
            num%=1000;
        }
        if(num>0){
            result+=numberToWordsWithThreeDIgit(num);
        }
        return result.trim();
    }

    public String numberToWordsWithThreeDIgit(int num){
        String result="";
        if(num>99){
            result+=" "+num1[num/100-1]+" Hundred";
        }
        num%=100;
        if(num>19){
            result+=" "+tens[num/10-2];
            num%=10;
        }else if(num>9){
            result+=" "+num2[num-10];
            num=0;
        }
        if(num>0){
            result+=" "+num1[num-1];
        }
        return result;
    }
}