Code Room
CodingMediumcod-g355
Subject BacktrackingLevel Mid–Senior~25 minCommon in Algorithms & data structures interviewsIndustries Software development

Question

Given a string s of digits only (length 1..12), return every valid IPv4 address that can be formed by inserting three dots into s without reordering or removing digits. Each of the four octets must be between 0 and 255 and may not have a leading zero unless it is exactly '0'. Return the addresses sorted ascending; return an empty list if none are valid.

Implement
restore_ip(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.

Vibe coding: describe the solution in plain language (or narrate it) and the coach grades your approach. Generating runnable code from your description is coming next.

Run or narrate your approach, then ask the coach.