23 lines
769 B
Elixir
23 lines
769 B
Elixir
defmodule LCS do
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def longest_common_substring(a,b) do
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alist = to_charlist(a) |> Enum.with_index
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blist = to_charlist(b) |> Enum.with_index
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lengths = for i <- 0..length(alist)-1, j <- 0..length(blist), into: %{}, do: {{i,j},0}
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Enum.reduce(alist, {lengths,0,""}, fn {x,i},acc ->
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Enum.reduce(blist, acc, fn {y,j},{map,gleng,lcs} ->
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if x==y do
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len = if i==0 or j==0, do: 1, else: map[{i-1,j-1}]+1
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map = %{map | {i,j} => len}
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if len > gleng, do: {map, len, String.slice(a, i - len + 1, len)},
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else: {map, gleng, lcs}
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else
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{map, gleng, lcs}
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end
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end)
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end)
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|> elem(2)
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end
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end
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IO.puts LCS.longest_common_substring("thisisatest", "testing123testing")
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