Valid IP addresses possible

valid_ip_addresses.py

class Solution(object):

    count = []

    def solve(self, s):
        self.helper(s, 0, 0, 0, [])
        addresses = []
        for a in self.count:
            prev = None
            add = None
            for c in a:
                if not add:
                    add = s[0:c + 1]
                else:
                    add += "."
                    add += s[prev + 1:c + 1]

                prev = c

            addresses.append(add)

        return addresses

    def helper(self, s, part_count, start_index, count, points):

        n = len(s)

        if part_count == 4 and start_index == n:
            self.count.append(points)

        if start_index == n:
            return 0

        for i in range(start_index, n):
            cur = s[start_index:i+1]
            if self.is_valid(cur):
                points.append(i)
                self.helper(s, part_count + 1, i+1, count, points[:])
                points.pop()

    def is_valid(self, s):

        if len(s) > 1 and s[0] == '0':
            return False
        n = int(s)

        if n > 255 or n < 0:
            return False

        return True


if __name__ == "__main__":
    s = "00000"
    ans = Solution().solve(s)
    print(ans)