{"id":1007,"date":"2015-01-27T06:00:19","date_gmt":"2015-01-27T04:00:19","guid":{"rendered":"http:\/\/www.glc.us.es\/~jalonso\/exercitium\/?p=1007"},"modified":"2015-02-03T07:55:50","modified_gmt":"2015-02-03T05:55:50","slug":"particiones-en-listas-de-segmentos","status":"publish","type":"post","link":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/particiones-en-listas-de-segmentos\/","title":{"rendered":"Particiones en listas de segmentos"},"content":{"rendered":"<h4>Exercitium<\/h4>\n<p>Definir la funci\u00f3n<\/p>\n<pre lang=\"text\">\n   particiones :: Int -> [a] -> [[[a]]]\n<\/pre>\n<p>tal que (particiones n xs) es la lista de listas de n elementos cuya  concatenaci\u00f3n es xs. Por ejemplo,<\/p>\n<pre lang=\"text\">\n   ghci> particiones 2 \"abc\"\n   [[\"\",\"abc\"],[\"a\",\"bc\"],[\"ab\",\"c\"],[\"abc\",\"\"]]\n   ghci> particiones 3 \"abc\"\n   [[\"\",\"\",\"abc\"],[\"\",\"a\",\"bc\"],[\"\",\"ab\",\"c\"],[\"\",\"abc\",\"\"],\n    [\"a\",\"\",\"bc\"],[\"a\",\"b\",\"c\"],[\"a\",\"bc\",\"\"],[\"ab\",\"\",\"c\"],\n    [\"ab\",\"c\",\"\"],[\"abc\",\"\",\"\"]]\n   ghci> length (particiones 4 \"abc\")\n   20\n<\/pre>\n<h4>Soluciones<\/h4>\n<pre lang=\"haskell\">\nparticiones :: Int -> [a] -> [[[a]]]\nparticiones 0 [] = [[]]\nparticiones 0 xs = []\nparticiones n xs = [ys:yss | (ys,zs) <- biparticiones xs,\n                             yss <- particiones (n-1) zs]\n\n-- (biparticiones xs) es la lista de los pares (xs1,xs2) tales que su\n-- concatenaci\u00f3n es xs. Por ejemplo, \n--    ghci> biparticiones \"abc\"\n--    [(\"\",\"abc\"),(\"a\",\"bc\"),(\"ab\",\"c\"),(\"abc\",\"\")]\nbiparticiones :: [a] -> [([a],[a])]\nbiparticiones []     = [([],[])]\nbiparticiones (x:xs) = ([],x:xs) :  \n                       [(x:xs1,xs2) | (xs1,xs2) <- biparticiones xs]\n<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>Exercitium Definir la funci\u00f3n particiones :: Int -> [a] -> [[[a]]] tal que (particiones n xs) es la lista de listas de n elementos cuya concatenaci\u00f3n es xs. Por ejemplo, ghci> particiones 2 \u00ababc\u00bb [[\u00ab\u00bb,\u00bbabc\u00bb],[\u00aba\u00bb,\u00bbbc\u00bb],[\u00abab\u00bb,\u00bbc\u00bb],[\u00ababc\u00bb,\u00bb\u00bb]] ghci> particiones 3 \u00ababc\u00bb [[\u00ab\u00bb,\u00bb\u00bb,\u00bbabc\u00bb],[\u00ab\u00bb,\u00bba\u00bb,\u00bbbc\u00bb],[\u00ab\u00bb,\u00bbab\u00bb,\u00bbc\u00bb],[\u00ab\u00bb,\u00bbabc\u00bb,\u00bb\u00bb], [\u00aba\u00bb,\u00bb\u00bb,\u00bbbc\u00bb],[\u00aba\u00bb,\u00bbb\u00bb,\u00bbc\u00bb],[\u00aba\u00bb,\u00bbbc\u00bb,\u00bb\u00bb],[\u00abab\u00bb,\u00bb\u00bb,\u00bbc\u00bb], [\u00abab\u00bb,\u00bbc\u00bb,\u00bb\u00bb],[\u00ababc\u00bb,\u00bb\u00bb,\u00bb\u00bb]] ghci> length (particiones 4 \u00ababc\u00bb) 20 Soluciones particiones :: Int -> [a] ->&#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":[8,6],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/1007"}],"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=1007"}],"version-history":[{"count":4,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/1007\/revisions"}],"predecessor-version":[{"id":1036,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/1007\/revisions\/1036"}],"wp:attachment":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/media?parent=1007"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/categories?post=1007"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/tags?post=1007"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}