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37 lines
784 B
Erlang
37 lines
784 B
Erlang
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% Find the largest prime factor of a composite number.
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% The prime factors of 13195 are 5, 7, 13 and 29.
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% What is the largest prime factor of the number 600851475143 ?
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-module(e003).
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-export([
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main/1,
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pfactor/1
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]).
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pfactor(N) ->
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pfactor_(N, []).
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pfactor_(N, F) ->
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Next = pfactor_next(N, 2),
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if
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Next == N ->
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[N | F];
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true ->
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pfactor_(trunc(N / Next), [Next | F])
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end.
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pfactor_next(N, Factor) ->
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if
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Factor == N ->
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Factor;
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N rem Factor == 0 ->
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Factor;
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true ->
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pfactor_next(N, Factor + 1)
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end.
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main(_) ->
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io:format("Prime Factors of 13195: ~w~n", [pfactor(13195)]),
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io:format("Prime Factors of 600851475143: ~w~n", [pfactor(600851475143)]).
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