https://leetcode.com/problems/integer-to-english-words/
Integer to English Words
Total Accepted: 5707 Total Submissions: 36483 Difficulty: Medium
Convert a non-negative integer to its english words representation. Given input is guaranteed to be less than 231 – 1.
For example,
123 -> "One Hundred Twenty Three" 12345 -> "Twelve Thousand Three Hundred Forty Five" 1234567 -> "One Million Two Hundred Thirty Four Thousand Five Hundred Sixty Seven"
Hint:
- Did you see a pattern in dividing the number into chunk of words? For example, 123 and 123000.
- Group the number by thousands (3 digits). You can write a helper function that takes a number less than 1000 and convert just that chunk to words.
Code (https://leetcode.com/discuss/55477/recursive-python):
def numberToWords(self, num):
to19 = 'One Two Three Four Five Six Seven Eight Nine Ten Eleven Twelve ' \
'Thirteen Fourteen Fifteen Sixteen Seventeen Eighteen Nineteen'.split()
tens = 'Twenty Thirty Forty Fifty Sixty Seventy Eighty Ninety'.split()
def words(n):
if n < 20:
return to19[n-1:n]
if n < 100:
return [tens[n/10-2]] + words(n%10)
if n < 1000:
return [to19[n/100-1]] + ['Hundred'] + words(n%100)
# p starts from 1
for p, w in enumerate(('Thousand', 'Million', 'Billion'), 1):
if n < 1000**(p+1):
return words(n/1000**p) + [w] + words(n%1000**p)
return ' '.join(words(num)) or 'Zero'
Idea:
Just use a recursive function to solve this problem. Nothing much to say.