Find Valid IP Addresses in Files

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

This problem is based on scanning a real directory tree. To make it deterministic for an online judge, the file system is provided as a nested dictionary named filesystem: a value that is a dict is a subdirectory, a value that is a str is a text file, and a value that is bytes or bytearray is a file that should be decoded as UTF-8 and skipped if decoding fails. Traverse every subdirectory, inspect every regular file, find all unique valid IPv4 addresses in the file contents, and return them sorted lexicographically as strings. A valid IPv4 address has exactly four decimal octets separated by dots; each octet must be between 0 and 255, and leading zeros are not allowed unless the octet is exactly 0.

Constraints

• 0 <= total number of files and folders <= 10^5
• The total length of all decodable file contents is at most 10^6 characters
• Only leaf values of type str, bytes, or bytearray should be treated as regular files

Examples

Example 1

Input: ({'readme.txt': 'Main IPs: 10.0.0.1 and 192.168.0.1. Invalid: 256.1.1.1, 192.168.001.1.', 'logs': {'today.log': b'Seen 10.0.0.1 twice and 0.0.0.0 once', 'bad.bin': b'\xff\xfe\xfa'}},)
Output: ['0.0.0.0', '10.0.0.1', '192.168.0.1']

Explanation: The valid unique addresses are 10.0.0.1, 192.168.0.1, and 0.0.0.0. The binary file bad.bin is skipped because it is not valid UTF-8. Addresses with 256 or leading zeros are invalid.

Example 2

Input: ({},)
Output: []

Explanation: An empty filesystem contains no files, so no IP addresses are found.

Hints

1. Use a stack or recursion to traverse the nested directory structure so you visit every subdirectory exactly once.
2. A regex can help you find dotted-number candidates, but you still need to validate each octet and reject leading zeros like 01.