面试题 16.08. 整数的英语表示

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"

Python 解答：

class Solution:
    def numberToWords(self, num: int) -> str:
        maps = {'0':"Zero", '1':'One', '2':'Two', '3':'Three', '4':'Four', '5':'Five', '6':'Six', '7':'Seven', '8':'Eight', '9':'Nine', '10':'Ten', '11':'Eleven', '12':'Twelve', '13':'Thirteen', '14':'Fourteen', '15':'Fifteen', '16':'Sixteen', '17':'Seventeen', '18':'Eighteen', '19':'Nineteen', '20':'Twenty', '30':'Thirty', '40':'Forty', '50':'Fifty', '60':'Sixty', '70':'Seventy', '80':'Eighty', '90':'Ninety'}
        units = ['Thousand', 'Million', 'Billion']
        def trans3digit(bits):
            if not bits:
                return ""
            if len(bits) == 1:
                return maps[bits]
            elif len(bits) == 2:
                if bits[0] == '0' and bits[1] == '0':
                    return ""
                elif bits[0] == '0' and bits[1] != '0':
                    return maps[bits[1]]
                elif bits[0] == '1' or bits[1] == '0':
                    return maps[bits]
                else:
                    return maps[bits[0]+'0'] +' '+ maps[bits[1]]
            elif len(bits) == 3:
                if bits[0] == '0' and bits[1] == '0' and bits[2] == '0':
                    return ""
                elif bits[0] != '0' and bits[1] == '0' and bits[2] == '0':
                    return maps[bits[0]]+' '+'Hundred'
                elif bits[0] == '0':
                    return trans3digit(bits[1:])
                else:
                    return maps[bits[0]]+' '+'Hundred'+' '+trans3digit(bits[1:])

        string = str(num)
        length = len(string)
        i = -1
        res = ""
        while length > 0:
            j = length
            k = length-3 if length-3 >= 0 else 0
            if i == -1:
                res = trans3digit(string[k:j])+ res
            else:
                temp = trans3digit(string[k:j])
                if temp and res:
                    res = temp+' '+units[i]+' '+ res
                elif temp:
                    res = temp+' '+units[i]
            length -= 3
            i += 1
        return res