273. Integer to English Words

Hard
Topics
Companies
Hint
Convert a non-negative integer num to its English words representation.

 

Example 1:

Input: num = 123
Output: "One Hundred Twenty Three"
Example 2:

Input: num = 12345
Output: "Twelve Thousand Three Hundred Forty Five"
Example 3:

Input: num = 1234567
Output: "One Million Two Hundred Thirty Four Thousand Five Hundred Sixty Seven"
 

Constraints:

0 <= num <= 231 - 1


solution:
class Solution {
    public String numberToWords(int num) {
        if(num == 0 ){
            return "Zero";
        }
        String[] bigString = new String[]{"Thousand","Million","Billion"};
        String result = numberToWordsHelper(num%1000);
        num = num/1000;
        if(num >0 && num %1000 >0){
            result = numberToWordsHelper(num %1000)+ "Thousand " +result;
        }
        num = num/1000;
        if(num >0 && num %1000 >0){
            result = numberToWordsHelper(num %1000)+ "Million "+ result;
        }
        num = num/1000;
        if(num >0 && num %1000 >0){
            result = numberToWordsHelper(num %1000)+"Billion "+result;
        }
        return result.trim();
    }
    public String numberToWordsHelper(int num){
        String[] digitString = new String[]{"Zero","One","Two","Three","Four","Five","Six","Seven","Eight","Nine"};
        String[] teenString = new String[]{"Ten","Eleven","Twelve","Thirteen","Fourteen","Fifteen","Sixteen","Seventeen","Eighteen","Nineteen"};
        String[] tenString = new String[]{"","","Twenty","Thirty","Forty","Fifty","Sixty","Seventy","Eighty","Ninety"};
        String result = "";
        if(num >99){
            result += digitString[num/100] + " Hundred ";
        }
        num = num %100;
        if(num < 20 && num >9){
            result += teenString[num%10]+ " ";
        }else{
            if(num >19){
                result += tenString[num/10] + " ";
            }
            num = num %10;
            if(num >0){
                result += digitString[num]+" ";
            }
        }
        return result;
    }
}


by this we can solve