PPOP.PY

numtowords.py

nums_1_19_1 = [
    None,
    "One",
    "Two",
    "Three",
    "Four",
    "Five",
    "Six",
    "Seven",
    "Eight",
    "Nine",
    "Ten",
    "Eleven",
    "Twelve",
    "Thirteen",
    "Fourteen",
    "Fifteen",
    "Sixteen",
    "Seventeen",
    "Eighteen",
    "Nineteen",
]

nums_20_90_10 = [
    None,
    None,
    "Twenty",
    "Thirty",
    "Forty",
    "Fifty",
    "Sixty",
    "Seventy",
    "Eighty",
    "Ninety",
]

powers_of_10 = [
    (1e9, "Billion"),
    (1e6, "Million"),
    (1e3, "Thousand"),
    (1e2, "Hundred"),
]

def concat_str(s1, s2):
    return f"{s1} {s2} "

class Solution:
    
    def numberToWords(self, num):
        if num == 0:
            return "Zero"
        return ' '.join(self.numberToWordsHelper(num).split())
    
    def numberToWordsHelper(self, num: int) -> str:
        # 1234567891
        
        if num == 0:
            return ""
        
        if num < 20:
            return nums_1_19_1[num]
        
        if num < 100:
            quant = int(num // 10)
            remainder = int(num % 10)
            return concat_str(nums_20_90_10[quant], self.numberToWordsHelper(remainder))

        remainder = num
        result = ""
        
        for power, name in powers_of_10:
            quant = int(remainder // power)
            remainder = int(remainder % power)
            
            if quant == 0:
                continue

            result += concat_str(
                self.numberToWordsHelper(quant),
                name
            )
            
        if remainder > 0:
            result += self.numberToWordsHelper(remainder)
        
        return result