Recover the Smallest Number

def solve(nums):
    nums = nums.split(',')
    from functools import cmp_to_key
    def compare(a, b):
        if a + b < b + a:
            return -1
        return 1
    nums.sort(key=cmp_to_key(compare))
    result = ''.join(nums).lstrip('0')
    print(result if result else '0')