A valid IP address consists of four numeric segments separated by single dots. Each segment must be an integer between 0 and 255 (inclusive), and leading zeros are not allowed unless the segment is exactly ‘0.”
For instance, “10.0.1.25” and “172.16.0.5” are valid IP addresses, while “01.200.100.3,” “256.100.50.25,” and “172.16.0.500” are invalid.
Given a string s made up of digits only, return all possible valid IP addresses that can be created by inserting exactly three dots into the string. You cannot rearrange or delete any digits. The resulting list of valid IP addresses can be returned in any order.
Constraints:
The naive approach would be to check all possible positions of the dots. Because an IP address requires inserting three dots, and if the input string contains 12 digits, then there are 11 possible positions between the digits where a dot can be placed. So, we initially have 11 choices for the first dot, then ...