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

asked Apr 3 at 11:24

Eli

212

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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

asked Apr 3 at 11:24

Eli

212

add a commentÂ |Â

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

asked Apr 3 at 11:24

Eli

212

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

asked Apr 3 at 11:24

Eli

212

asked Apr 3 at 11:24

Eli

212

asked Apr 3 at 11:24

Eli

212

asked Apr 3 at 11:24

Eli

212

add a commentÂ |Â

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