{"id":7324,"date":"2022-09-07T06:00:00","date_gmt":"2022-09-07T04:00:00","guid":{"rendered":"http:\/\/www.glc.us.es\/~jalonso\/exercitium\/?p=7324"},"modified":"2022-12-14T16:31:06","modified_gmt":"2022-12-14T14:31:06","slug":"permutacion-ciclica","status":"publish","type":"post","link":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/permutacion-ciclica\/","title":{"rendered":"Permutaci\u00f3n c\u00edclica"},"content":{"rendered":"<p>Definir la funci\u00f3n<\/p>\n<pre lang=\"text\">\n   ciclo :: [a] -> [a]\n<\/pre>\n<p>tal que <code>(ciclo xs)<\/code> es la lista obtenida permutando c\u00edclicamente los elementos de la lista <code>xs<\/code>, pasando el \u00faltimo elemento al principio de la lista. Por ejemplo,<\/p>\n<pre lang=\"text\">\n   ciclo [2,5,7,9]  == [9,2,5,7]\n   ciclo []         == []\n   ciclo [2]        == [2]\n<\/pre>\n<p>Comprobar que la longitud es un invariante de la funci\u00f3n ciclo; es decir, la longitud de <code>(ciclo xs)<\/code> es la misma que la de <code>xs<\/code>.<\/p>\n<p><b>Soluciones<\/b><\/p>\n<p>A continuaci\u00f3n se muestran las <a href=\"#haskell\">soluciones en Haskell<\/a> y las <a href=\"#python\">soluciones en Python<\/a>.<\/p>\n<p><a name=\"haskell\"><\/a><br \/>\n<b>Soluciones en Haskell<\/b><\/p>\n<pre lang=\"haskell\">\nimport Test.QuickCheck\n\nciclo :: [a] -> [a]\nciclo [] = []\nciclo xs = last xs : init xs\n\n-- La propiedad es\nprop_ciclo :: [Int] -> Bool\nprop_ciclo xs = length (ciclo xs) == length xs\n\n-- La comprobaci\u00f3n es\n--    \u03bb> quickCheck prop_ciclo\n--    +++ OK, passed 100 tests.\n<\/pre>\n<p>El c\u00f3digo se encuentra en <a href=\"https:\/\/github.com\/jaalonso\/Exercitium\/blob\/main\/src\/Permutacion_ciclica.hs\">GitHub<\/a><\/p>\n<p><a name=\"python\"><\/a><br \/>\n<b>Soluciones en Python<\/b><\/p>\n<pre lang=\"python\">\nfrom typing import TypeVar\nfrom hypothesis import given, strategies as st\n\nA = TypeVar('A')\n\ndef ciclo(xs: list[A]) -> list[A]:\n    if xs:\n        return [xs[-1]] + xs[:-1]\n    return []\n\n# La propiedad de es\n@given(st.lists(st.integers()))\ndef test_equiv_ciclo(xs):\n    assert len(ciclo(xs)) == len(xs)\n\n# La comprobaci\u00f3n es\n#    src> poetry run pytest -q permutacion_ciclica.py\n#    1 passed in 0.39s\n<\/pre>\n<p>El c\u00f3digo se encuentra en <a href=\"https:\/\/github.com\/jaalonso\/Exercitium-Python\/blob\/main\/src\/permutacion_ciclica.py\">GitHub<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Definir la funci\u00f3n ciclo :: [a] -> [a] tal que (ciclo xs) es la lista obtenida permutando c\u00edclicamente los elementos de la lista xs, pasando el \u00faltimo elemento al principio de la lista. Por ejemplo, ciclo [2,5,7,9] == [9,2,5,7] ciclo [] == [] ciclo [2] == [2] Comprobar que la longitud es un invariante de&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_kad_post_transparent":"","_kad_post_title":"","_kad_post_layout":"","_kad_post_sidebar_id":"","_kad_post_content_style":"","_kad_post_vertical_padding":"","_kad_post_feature":"","_kad_post_feature_position":"","_kad_post_header":false,"_kad_post_footer":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"footnotes":"","_jetpack_memberships_contains_paid_content":false},"categories":[581],"tags":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/7324"}],"collection":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/comments?post=7324"}],"version-history":[{"count":3,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/7324\/revisions"}],"predecessor-version":[{"id":7697,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/7324\/revisions\/7697"}],"wp:attachment":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/media?parent=7324"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/categories?post=7324"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/tags?post=7324"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}