76 lines
1.1 KiB
Erlang
76 lines
1.1 KiB
Erlang
-module(lib_misc).
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-export([
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for/3,
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qsort/1,
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pythag/1,
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perms/1,
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kabs/1,
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kfilter/2,
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kclassify/1,
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stash_term/2,
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retrieve_term/1
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]).
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for(Max, Max, F) ->
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[F(Max)];
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for(I, Max, F) ->
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[F(I)|for(I+1, Max, F)].
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qsort([]) ->
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[];
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qsort([Pivot|T]) ->
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qsort([X || X <- T,
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X < Pivot])
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++
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[Pivot]
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++
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qsort([X || X <- T,
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X >= Pivot]).
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pythag(N) ->
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[{A,B,C} ||
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A <- lists:seq(1,N),
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B <- lists:seq(1,N),
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C <- lists:seq(1,N),
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A+B+C =< N,
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A*A+B*B =:= C*C
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].
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perms([]) ->
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[[]];
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perms(L) ->
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[[H|T] || H <- L,
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T <- perms(L--[H])].
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kabs(V) when is_integer(V), V >= 0 ->
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V;
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kabs(V) when is_integer(V) -> -V.
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kfilter(P, [H|T]) ->
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case P(H) of
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true -> [H|kfilter(P, T)];
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false -> kfilter(P, T)
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end;
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kfilter(_, []) -> [].
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kclassify(N) ->
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if
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N >= 10 ->
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high;
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N >= 3 ->
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medium;
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true ->
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low
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end.
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stash_term(Path, Term) ->
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file:write_file(Path, erlang:term_to_binary(Term)).
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retrieve_term(Path) ->
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case file:read_file(Path) of
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{ok, BinaryTerm} ->
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erlang:binary_to_term(BinaryTerm);
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{error, Reason} -> throw({read_file, Reason})
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end.
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