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Group Anagrams at Apple — Interview Guide

How to approach Group Anagrams in a Apple interview: the optimal approach, what Apple interviewers look for, and company-specific tips.

Updated 2026-09MediumArrays & Hashing

The problem at Apple

Given an array of strings, group the anagrams together. An anagram group contains strings that are rearrangements of the same letters.

Apple uses this problem to assess craft, detail, and domain depth. Expect Apple-specific follow-ups that tie the solution back to production reasoning and the company's engineering bar.

Key concepts

Sorting each string gives a canonical key — O(k log k) per string.
A 26-character count tuple is a key in O(k) per string and is faster for long strings.
Both produce the same groups; the count key wins when strings are long.

Approach

import collections
def group_anagrams(strs):
    groups = collections.defaultdict(list)
    for s in strs:
        key = [0] * 26
        for c in s:
            key[ord(c) - 97] += 1
        groups[tuple(key)].append(s)
    return list(groups.values())

What Apple looks for

Domain expertise relevant to the team.
Craft — performance, edge cases, and polish.
Passion for the product and user experience.
Independence and ownership of a feature end-to-end.

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