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Group Anagrams at Uber — Interview Guide

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

Updated 2026-09MediumArrays & Hashing

The problem at Uber

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

Uber uses this problem to assess real-time systems and marketplaces. Expect Uber-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 Uber looks for

Real-time and distributed systems intuition.
Geospatial and concurrency reasoning.
Pragmatic, production-minded engineering.
Ownership of features end-to-end.

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