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.

What difficulty level is this interview question?

This is a medium difficulty Coding & Algorithms question, commonly asked during Technical Screen rounds at Amazon.

What role is this question designed for?

This question is commonly asked for Software Engineer candidates at Amazon during technical interviews.

Find Valid IP Addresses in Files | Amazon Interview Question

Quick Overview

This question evaluates file system traversal, recursive I/O handling, text parsing and pattern recognition, input validation for IPv4 formatting, deduplication, and ordered output; it is in the Coding & Algorithms category and emphasizes practical application over purely conceptual understanding.

You are given an absolute or relative path to a directory on the local file system.

Write a program that recursively traverses every subdirectory under that root directory, reads every regular file, finds all valid IPv4 addresses contained in those files, and prints the addresses in lexicographic order.

A valid IPv4 address has exactly four decimal octets separated by dots. Each octet must be an integer from 0 to 255. Leading zeros are not allowed unless the octet is exactly 0. For example, 192.168.0.1 and 0.0.0.0 are valid, while 256.1.1.1, 01.2.3.4, 1.2.3, and 1.2.3.4.5 are invalid.

Clarifications:

Recursively visit all nested folders under the input path.
Only scan regular files.
Treat file contents as text; if a file cannot be decoded or read, handle it gracefully according to your language's best practices.
If the same valid IP address appears multiple times, print it only once.
The final output should contain one IP address per line, sorted lexicographically as strings.

Find Valid IP Addresses in Files

Quick Overview

Find Valid IP Addresses in Files

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