Code RoomRestore IP addresses
MediumPrep Room Coding #442

Restore IP addresses

CodingAlgorithms & data structuresMid–Senior~25 min

Given a string of digits, return every valid IPv4 address that can be formed by inserting three dots, splitting it into four parts. Each part is 0-255 with no leading zeros (except the single digit '0'). Return the addresses sorted lexicographically. Input length is at most 12.

Implement
restore_ip_addresses(s: str) → list[str]
Examples
in["25525511135"]out["255.255.11.135","255.255.111.35"]
What a strong answer looks like

State your approach and its time/space complexity out loud before you optimize. Handle the edge cases (empty input, duplicates, overflow), and say why you chose this over the brute force. Green tests are the floor, not the grade.

0:00 of about 25 min
InputExpectedGot
["25525511135"]["255.255.11.135","255.255.111.35"]not run yetsample