Permutations: Difference between revisions
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(→{{header|Mercury}}: output) |
(→{{header|Mathematica}}: added version defining permutations from scratch) |
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=={{header|Mathematica}}== |
=={{header|Mathematica}}== |
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Version from scratch: |
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<lang Mathematica> |
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(***Standard list functions:*) |
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fold[f_, x_, {}] := x |
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fold[f_, x_, {h_, t___}] := fold[f, f[x, h], {t}] |
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insert[L_, x_, n_] := Join[L[[;; n - 1]], {x}, L[[n ;;]]] |
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(***Generate all permutations of a set S:*) |
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permutations[S_] := |
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fold[Join @@ (Function[{L}, |
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Table[insert[L, #2, k + 1], {k, 0, Length[L]}]] /@ #1) &, {{}}, |
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S] |
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</lang> |
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Built-in version: |
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<lang Mathematica>Permutations[{1,2,3,4}]</lang> |
<lang Mathematica>Permutations[{1,2,3,4}]</lang> |
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{{out}} |
{{out}} |
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