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Problem

Group Anagrams

LeetCode #49Medium

Bucket words by their sorted-letter signature

Given an array of strings, group together the ones that are anagrams of each other (use every word exactly once). Return the groups in any order.

Asked atAmazonUberFacebook

Brute force · pairwise

time O(n²·k log k)space O(n·k)

step 1 / 27

eat

tea

tan

ate

nat

bat

[0][1][2][3][4][5]

Brute force · pairwise


▸
1given words
2for i ← 0 to n − 1 (if word i not yet grouped):
3    start group with words[i]
4    for j ← i + 1 to n − 1:
5        if sorted(words[i]) == sorted(words[j]): add words[j]
6return all groups

state

line 1Group words that are anagrams of each other. Two words are anagrams when sorting their letters gives the same string — so we can test any pair by comparing sorted(a) with sorted(b).