{"id":2652,"date":"2016-12-05T06:00:51","date_gmt":"2016-12-05T04:00:51","guid":{"rendered":"http:\/\/www.glc.us.es\/~jalonso\/exercitium\/?p=2652"},"modified":"2016-12-12T16:57:33","modified_gmt":"2016-12-12T14:57:33","slug":"listas-engarzadas","status":"publish","type":"post","link":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/listas-engarzadas\/","title":{"rendered":"Listas engarzadas"},"content":{"rendered":"<p>Una lista de listas es <strong>engarzada<\/strong> si el \u00faltimo elemento de cada lista coincide con el primero de la siguiente.<\/p>\n<p>Definir la funci\u00f3n<\/p>\n<pre lang=\"text\">\n   engarzada :: Eq a => [[a]] -> Bool\n<\/pre>\n<p>tal que (engarzada xss) se verifica si xss es una lista engarzada. Por ejemplo,<\/p>\n<pre lang=\"text\">\n   engarzada [[1,2,3], [3,5], [5,9,0]] == True\n   engarzada [[1,4,5], [5,0], [1,0]]   == False\n   engarzada [[1,4,5], [], [1,0]]      == False\n   engarzada [[2]]                     == True\n<\/pre>\n<h4>Soluciones<\/h4>\n<pre lang=\"haskell\">\n-- 1\u00aa soluci\u00f3n:\nengarzada :: Eq a => [[a]] -> Bool\nengarzada (xs:ys:xss) =\n     not (null xs) && not (null ys) && last xs == head ys\n  && engarzada (ys:xss)\nengarzada _ = True\n\n-- 2\u00aa soluci\u00f3n:\nengarzada2 :: Eq a => [[a]] -> Bool\nengarzada2 (xs:ys:xss) =\n  and [ not (null xs)\n      , not (null ys)\n      , last xs == head ys\n      , engarzada2 (ys:xss) ]\nengarzada2 _ = True\n\n-- 3\u00aa soluci\u00f3n:\nengarzada3 :: Eq a => [[a]] -> Bool\nengarzada3 xss =\n  and [ not (null xs) && not (null ys) && last xs == head ys\n      | (xs,ys) <- zip xss (tail xss)]\n\n-- 4\u00aa soluci\u00f3n:\nengarzada4 :: Eq a => [[a]] -> Bool\nengarzada4 xss =\n  all engarzados (zip xss (tail xss))\n  where engarzados (xs,ys) =\n          not (null xs) && not (null ys) && last xs == head ys\n\n-- 5\u00aa soluci\u00f3n:\nengarzada5 :: Eq a => [[a]] -> Bool\nengarzada5 xss =\n  all engarzados (zip xss (tail xss))\n  where engarzados ([],_)   = False\n        engarzados (_,[])   = False\n        engarzados (xs,y:_) = last xs == y\n\n-- 6\u00aa soluci\u00f3n:\nengarzada6 :: Eq a => [[a]] -> Bool\nengarzada6 xss =\n  and (zipWith engarzados xss (tail xss))\n  where engarzados [] _     = False\n        engarzados _  []    = False\n        engarzados xs (y:_) = last xs == y\n<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>Una lista de listas es engarzada si el \u00faltimo elemento de cada lista coincide con el primero de la siguiente. Definir la funci\u00f3n engarzada :: Eq a => [[a]] -> Bool tal que (engarzada xss) se verifica si xss es una lista engarzada. Por ejemplo, engarzada [[1,2,3], [3,5], [5,9,0]] == True engarzada [[1,4,5], [5,0], [1,0]]&#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":[41,100,71,134,181,141,11,6,9],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/2652"}],"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=2652"}],"version-history":[{"count":4,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/2652\/revisions"}],"predecessor-version":[{"id":2686,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/2652\/revisions\/2686"}],"wp:attachment":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/media?parent=2652"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/categories?post=2652"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/tags?post=2652"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}