Anagram Substring Search (Find All Anagrams / indexOf)

Problem Overview

Implement a function anagram_index(lookup, query) that returns the index of the first occurrence of an anagram of query as a consecutive substring in lookup. Return -1 if no such substring exists. Equivalently, given a string s and a pattern p, find the starting index (or all starting indices) of every…

• 4 candidate-reported follow-ups — the exact probes interviewers asked, with the trigger for each
• The rest of the problem statement — full requirements, constraints, and edge cases
• Approach and trade-offs — what passing candidates did, and the mistakes that sink people