Find first CIDR block covering IP

Q: Find first CIDR block covering IP

This is a Coding & Algorithms interview question from Databricks for Software Engineer roles. View the full question and solution on PracHub.

Q: How do I approach Coding & Algorithms interview questions?

Coding & Algorithms questions require understanding of core concepts and practice. PracHub provides solutions with explanations to help you master coding & algorithms interviews.

Question

You are given:

A single IPv4 address as a string, e.g. "192.168.1.5" .
A list of CIDR blocks (IPv4), each as a string in the form "a.b.c.d/x" , where 0 <= a,b,c,d <= 255 and 0 <= x <= 32 .

Each CIDR block a.b.c.d/x represents all IP addresses whose first x bits are identical to the first x bits of the base address a.b.c.d.

Task:

Return the first CIDR block in the given list that covers (contains) the given IP address. If none of the CIDR blocks contains the IP, return some designated value such as null or an empty string.

Clarifications:

"First" means the first element in the input list order that matches.
Assume IPv4 only.
You may assume the input strings are syntactically valid.
Aim for an efficient solution that can handle up to, for example, 10^5 CIDR blocks.

Define clearly what you return when there is no matching CIDR.

Find first CIDR block covering IP

Comments (0)