Next Largest Number

Write a function that returns the next number that can be created from the same digits as the input.

Examples

next_number(19) ➞ 91

next_number(3542) ➞ 4235

next_number(5432) ➞ 5432

next_number(58943) ➞ 59348

Notes

• If no larger number can be formed, return the number itself.
• Bonus: See if you can do this without generating all digit permutations.