Group Anagrams at Meta — Interview Guide

• 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.

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())

• Coding speed and correctness — produce working, optimal code quickly.
• Scale thinking — design for billions of users in the system design round.
• Builder mindset — bias toward shipping and measuring.
• Behavioral: impact, collaboration, and handling ambiguity.