{"id":1766,"date":"2015-11-26T06:00:10","date_gmt":"2015-11-26T04:00:10","guid":{"rendered":"http:\/\/www.glc.us.es\/~jalonso\/exercitium\/?p=1766"},"modified":"2016-05-01T20:41:45","modified_gmt":"2016-05-01T18:41:45","slug":"repeticiones-segun-la-posicion","status":"publish","type":"post","link":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/repeticiones-segun-la-posicion\/","title":{"rendered":"Repeticiones seg\u00fan la posici\u00f3n"},"content":{"rendered":"<p>Definir la funci\u00f3n<\/p>\n<pre lang=\"text\">\n   transformada :: [a] -> [a]\n<\/pre>\n<p>tal que (transformada xs) es la lista obtenida repitiendo cada elemento tantas veces como indica su posici\u00f3n en la lista. Por ejemplo,<\/p>\n<pre lang=\"text\">\n   transformada [7,2,5] == [7,2,2,5,5,5]\n   transformada \"eco\"   == \"eccooo\"\n<\/pre>\n<p>Comprobar con QuickCheck si la transformada de una lista de n n\u00fameros enteros, con n \u2265 2, tiene menos de n\u00b3 elementos.<\/p>\n<h4>Soluciones<\/h4>\n<pre lang=\"haskell\">\nimport Test.QuickCheck\n\ntransformada :: [a] -> [a]\ntransformada xs = concat [replicate n x | (n,x) <- zip [1..] xs]\n\n-- La propiedad es\nprop_transformada :: [Int] -> Property\nprop_transformada xs = n >= 2 ==> length (transformada xs) < n^3\n    where n = length xs\n\n-- La comprobaci\u00f3n es\n--    ghci> quickCheck prop_transformada\n--    +++ OK, passed 100 tests.\n<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>Definir la funci\u00f3n transformada :: [a] -> [a] tal que (transformada xs) es la lista obtenida repitiendo cada elemento tantas veces como indica su posici\u00f3n en la lista. Por ejemplo, transformada [7,2,5] == [7,2,2,5,5,5] transformada \u00abeco\u00bb == \u00abeccooo\u00bb Comprobar con QuickCheck si la transformada de una lista de n n\u00fameros enteros, con n \u2265 2,&#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":[4],"tags":[8,12,28,19,146,9],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/1766"}],"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=1766"}],"version-history":[{"count":6,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/1766\/revisions"}],"predecessor-version":[{"id":2386,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/1766\/revisions\/2386"}],"wp:attachment":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/media?parent=1766"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/categories?post=1766"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/tags?post=1766"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}