LeetCode-in-All

49. Group Anagrams

Medium

Given an array of strings strs, group the anagrams together. You can return the answer in any order.

An Anagram is a word or phrase formed by rearranging the letters of a different word or phrase, typically using all the original letters exactly once.

Example 1:

Input: strs = [“eat”,”tea”,”tan”,”ate”,”nat”,”bat”]

Output: [[“bat”],[“nat”,”tan”],[“ate”,”eat”,”tea”]]

Example 2:

Input: strs = [””]

Output: [[””]]

Example 3:

Input: strs = [“a”]

Output: [[“a”]]

Constraints:

• 1 <= strs.length <= 104
• 0 <= strs[i].length <= 100
• strs[i] consists of lowercase English letters.

Solution

-spec group_anagrams(Strs :: [unicode:unicode_binary()]) -> [[unicode:unicode_binary()]].
group_anagrams(Strs) ->
    AnagramMap = group_anagrams_helper(Strs, #{}),
    maps:values(AnagramMap).

group_anagrams_helper([Head | Tail], Acc) ->
    NewString = sort_string(Head),
    NewMap = case maps:is_key(NewString, Acc) of
        true ->
            maps:update(NewString, [Head | maps:get(NewString, Acc)], Acc);
        false ->
            maps:put(NewString, [Head], Acc)
    end,
    group_anagrams_helper(Tail, NewMap);
group_anagrams_helper([], Acc) ->
    Acc.

sort_string(Str) ->
    StrList = binary_to_list(Str),        % Convert string to list of characters
    SortedList = lists:sort(StrList),       % Sort the list of characters
    list_to_binary(SortedList).

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