How should I practice IP Address to CIDR Blocks?

Start by reading the full statement, solve the visible examples, then compare the pattern against related OpenAI phone screen problems in FastPrep.

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FastPrep tags this as a OpenAI phone screen coding practice problem when the problem catalog has that company and stage context.

Problem · Bit Manipulation

IP Address to CIDR Blocks

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Problem statement

Given a starting IPv4 address startIp and a positive integer count, return the minimum set of CIDR blocks that exactly covers the count consecutive IPv4 addresses starting at startIp.

Each CIDR block must be written in the form a.b.c.d/prefix. The returned blocks must cover the range exactly and use the minimum possible number of blocks.

You may assume the input is a valid IPv4 address and that the range stays within the IPv4 space.

Function

ipRangeToCidrBlocks(startIp: String, count: long) → String[]

Complete the function ipRangeToCidrBlocks in the editor below.

ipRangeToCidrBlocks has the following parameters:

String startIp: the first IPv4 address in the range
long count: the number of consecutive IPv4 addresses to cover

Returns

String[]: the minimum CIDR cover for the range.

Examples

Example 1

startIp = "0.0.0.0"count = 1return = ["0.0.0.0/32"]

A single IPv4 address is represented by a /32 CIDR block.

Example 2

startIp = "0.0.0.0"count = 256return = ["0.0.0.0/24"]

The range from 0.0.0.0 through 0.0.0.255 is exactly one /24 block.

Constraints

1 <= count <= 2^32
startIp is a valid IPv4 address.
The answer must cover exactly the requested range using the minimum number of blocks.