Recursive solution for Longest Substring Without Repeating Characters written in Elixir

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Here's my recursive implementation of a sliding window algorithm to find the longest substring of a given string without repeating characters. Is there a more idiomatic-Elixir way to write this?



defmodule MyString do
 def length_of_longest_substring(string), do: string |> length_of_longest_substring(0, 0, 0, %)

 defp length_of_longest_substring(string, start_index, end_index, longest, indexes) do
 if end_index >= String.length(string) do
 longest
 else
 currrent_char = String.at(string, end_index)
 previous_occurrence = Map.get(indexes, currrent_char, -1)
 updated_indexes = Map.put(indexes, currrent_char, end_index)

 cond do
 previous_occurrence >= start_index ->
 string |> length_of_longest_substring(previous_occurrence + 1, end_index, longest, updated_indexes)

 true ->
 longest = max(longest, end_index - start_index + 1)

 string |> length_of_longest_substring(start_index, end_index + 1, longest, updated_indexes)
 end
 end
 end
end



algorithm recursion functional-programming elixir




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    up vote
    4
    down vote

    favorite












    Here's my recursive implementation of a sliding window algorithm to find the longest substring of a given string without repeating characters. Is there a more idiomatic-Elixir way to write this?



    defmodule MyString do
     def length_of_longest_substring(string), do: string |> length_of_longest_substring(0, 0, 0, %)

     defp length_of_longest_substring(string, start_index, end_index, longest, indexes) do
     if end_index >= String.length(string) do
     longest
     else
     currrent_char = String.at(string, end_index)
     previous_occurrence = Map.get(indexes, currrent_char, -1)
     updated_indexes = Map.put(indexes, currrent_char, end_index)

     cond do
     previous_occurrence >= start_index ->
     string |> length_of_longest_substring(previous_occurrence + 1, end_index, longest, updated_indexes)

     true ->
     longest = max(longest, end_index - start_index + 1)

     string |> length_of_longest_substring(start_index, end_index + 1, longest, updated_indexes)
     end
     end
     end
    end



    algorithm recursion functional-programming elixir




    share|improve this question





















      up vote
      4
      down vote

      favorite









      up vote
      4
      down vote

      favorite











      Here's my recursive implementation of a sliding window algorithm to find the longest substring of a given string without repeating characters. Is there a more idiomatic-Elixir way to write this?



      defmodule MyString do
       def length_of_longest_substring(string), do: string |> length_of_longest_substring(0, 0, 0, %)

       defp length_of_longest_substring(string, start_index, end_index, longest, indexes) do
       if end_index >= String.length(string) do
       longest
       else
       currrent_char = String.at(string, end_index)
       previous_occurrence = Map.get(indexes, currrent_char, -1)
       updated_indexes = Map.put(indexes, currrent_char, end_index)

       cond do
       previous_occurrence >= start_index ->
       string |> length_of_longest_substring(previous_occurrence + 1, end_index, longest, updated_indexes)

       true ->
       longest = max(longest, end_index - start_index + 1)

       string |> length_of_longest_substring(start_index, end_index + 1, longest, updated_indexes)
       end
       end
       end
      end



      algorithm recursion functional-programming elixir




      share|improve this question











      Here's my recursive implementation of a sliding window algorithm to find the longest substring of a given string without repeating characters. Is there a more idiomatic-Elixir way to write this?



      defmodule MyString do
       def length_of_longest_substring(string), do: string |> length_of_longest_substring(0, 0, 0, %)

       defp length_of_longest_substring(string, start_index, end_index, longest, indexes) do
       if end_index >= String.length(string) do
       longest
       else
       currrent_char = String.at(string, end_index)
       previous_occurrence = Map.get(indexes, currrent_char, -1)
       updated_indexes = Map.put(indexes, currrent_char, end_index)

       cond do
       previous_occurrence >= start_index ->
       string |> length_of_longest_substring(previous_occurrence + 1, end_index, longest, updated_indexes)

       true ->
       longest = max(longest, end_index - start_index + 1)

       string |> length_of_longest_substring(start_index, end_index + 1, longest, updated_indexes)
       end
       end
       end
      end




      algorithm recursion functional-programming elixir





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      asked Apr 3 at 11:24









      Eli

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