Ackermann function: Difference between revisions
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=={{header|Prolog}}== |
=={{header|Prolog}}== |
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{{works with|SWI Prolog}} |
{{works with|SWI Prolog}} |
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<lang prolog>ack |
<lang prolog>:- table ack/3. % memoization reduces the execution time of ack(4,1,X) from several |
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% minutes to about one second on a typical desktop computer. |
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ack(0, N, Ans) :- Ans is N+1. |
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ack(M, 0, Ans) :- M>0, X is M-1, ack(X, 1, Ans). |
ack(M, 0, Ans) :- M>0, X is M-1, ack(X, 1, Ans). |
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ack(M, N, Ans) :- M>0, N>0, X is M-1, Y is N-1, ack(M, Y, Ans2), ack(X, Ans2, Ans).</lang> |
ack(M, N, Ans) :- M>0, N>0, X is M-1, Y is N-1, ack(M, Y, Ans2), ack(X, Ans2, Ans).</lang> |
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