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"
O(n)
O(n)
Run make to build and run C++ files and run Swift files. Or you can run .playground file.