Integer to English Words

class Solution(object):
    def numberToWords(self, num):
        """
        :type num: int
        :rtype: str
        """
        if num==0:
            return 'Zero'
        ddict = {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'}
        base = ['', 'Thousand', 'Million', 'Billion']
        res=''
        i,t=0,0
        while num:
            t=num%1000
            if t:
                res=base[i]+' '+res
                one=t%10
                two=t%100-one
                three=t/100
                if two==10:
                    res=ddict[one+two]+' '+res
                else:
                    if one:
                        res=ddict[one]+' '+res
                    if two:
                        res=ddict[two]+' '+res
                if three:
                    res=ddict[three]+' Hundred '+res
            num=num/1000
            i+=1
        return res.rstrip()