# 3ms Java solution beats 97.90%

• The code explains itself.

``````private String[] units = {"Zero", "One", "Two", "Three", "Four", "Five", "Six", "Seven", "Eight", "Nine"};
private String[] tenToTwenty = {"Ten", "Eleven", "Twelve", "Thirteen", "Fourteen", "Fifteen", "Sixteen", "Seventeen", "Eighteen", "Nineteen"};
private String[] tens = {"", "", "Twenty", "Thirty", "Forty", "Fifty", "Sixty", "Seventy", "Eighty", "Ninety"};

public String numberToWords(int num) {
if (num < 0) return "";
if (num < 10) return units[num];
if (num < 20) return tenToTwenty[num - 10];
if (num < 100) return tens[num / 10] + (num % 10 == 0 ? "" : " " + numberToWords(num % 10));
if (num < 1000) return numberToWords(num / 100) + " Hundred" + (num % 100 == 0 ? "" : " " + numberToWords(num % 100));
if (num < 1000000) return numberToWords(num / 1000) + " Thousand" + (num % 1000 == 0 ? "" : " " + numberToWords(num % 1000));
if (num < 1000000000) return numberToWords(num / 1000000) + " Million" + (num % 1000000 == 0 ? "" : " " + numberToWords(num % 1000000));

return numberToWords(num / 1000000000) + " Billion" + (num % 1000000000 == 0 ? "" : " " + numberToWords(num % 1000000000));
}
``````

• very impressive

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