Practice/Meta/Leetcode 1108. Defanging an IP Address

Leetcode 1108. Defanging an IP Address

CodingOptional

Problem

You are building a security tool that needs to sanitize URLs before displaying them in logs or documentation. Your task is to create a function that takes a URL string and returns a "sanitized" version where the colon in the protocol (like http: or https:) is replaced with [:].

This sanitization helps prevent URLs from being automatically converted into clickable links in certain contexts, making them safer to display in plain text environments.

Requirements

1. Replace only the first colon in the URL (the one that appears after the protocol name)
2. The replacement should change : to [:]
3. Return the modified URL as a string
4. All other characters in the URL should remain unchanged

Constraints

• The input string will always be a valid URL starting with a protocol (e.g., http://, https://, ftp://)
• The URL length will be between 10 and 1000 characters
• You may assume the input is always a well-formed URL
• Time complexity should be O(n) where n is the length of the URL
• Space complexity should be O(n) for the result string

Examples

Example 1:

Input: "https://google.com" Output: "https[:]//google.com" Explanation: The colon after "https" is replaced with "[:]"

Example 2:

Input: "http://example.com:3000/api/users" Output: "http[:]//example.com:3000/api/users" Explanation: Only the protocol colon is replaced. The port number colon remains unchanged.

Example 3:

Input: "ftp://files.company.net/downloads" Output: "ftp[:]//files.company.net/downloads" Explanation: Works with any protocol, not just HTTP/HTTPS