{"id":4490,"date":"2019-01-01T06:00:18","date_gmt":"2019-01-01T04:00:18","guid":{"rendered":"http:\/\/www.glc.us.es\/~jalonso\/exercitium\/?p=4490"},"modified":"2019-01-08T10:11:50","modified_gmt":"2019-01-08T08:11:50","slug":"el-2019-es-apocaliptico","status":"publish","type":"post","link":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/el-2019-es-apocaliptico\/","title":{"rendered":"El 2019 es apocal\u00edptico"},"content":{"rendered":"<p>Un n\u00famero natural n es <a href=\"http:\/\/bit.ly\/2RqeeNk\">apocal\u00edptico<\/a> si 2^n contiene la secuencia 666. Por ejemplo, 157 es apocal\u00edptico porque 2^157 es 182687704666362864775460604089535377456991567872 que contiene la secuencia 666.<\/p>\n<p>Definir las funciones<\/p>\n<pre lang=\"text\">\n   esApocaliptico       :: Integer -> Bool\n   apocalipticos        :: [Integer]\n   posicionApocaliptica :: Integer -> Maybe Int\n<\/pre>\n<p>tales que<\/p>\n<ul>\n<li>(esApocaliptico n) se verifica si n es un n\u00famero apocal\u00edptico. Por ejemplo,<\/li>\n<\/ul>\n<pre lang=\"text\">  \n     esApocaliptico 157   ==  True\n     esApocaliptico 2019  ==  True\n     esApocaliptico 2018  ==  False\n<\/pre>\n<ul>\n<li>apocalipticos es la lista de los n\u00fameros apocal\u00edpticos. Por ejemplo,<\/li>\n<\/ul>\n<pre lang=\"text\">  \n     take 9 apocalipticos  ==  [157,192,218,220,222,224,226,243,245]\n     apocalipticos !! 450  ==  2019\n<\/pre>\n<ul>\n<li>(posicionApocalitica n) es justo la posici\u00f3n de n en la sucesi\u00f3n de n\u00fameros apocal\u00edpticos, si n es apocal\u00edptico o Nothing, en caso contrario. Por ejemplo,<\/li>\n<\/ul>\n<pre lang=\"text\">  \n     posicionApocaliptica 157   ==  Just 0\n     posicionApocaliptica 2019  ==  Just 450\n     posicionApocaliptica 2018  ==  Nothing\n<\/pre>\n<h4>Soluciones<\/h4>\n<pre lang=\"haskell\">\nimport Data.List (isInfixOf, elemIndex)\n\n-- 1\u00aa definici\u00f3n de esApocaliptico\nesApocaliptico :: Integer -> Bool\nesApocaliptico n = \"666\" `isInfixOf` show (2^n)\n\n-- 2\u00aa definici\u00f3n de esApocaliptico\nesApocaliptico2 :: Integer -> Bool\nesApocaliptico2 = isInfixOf \"666\" . show . (2^)\n\n-- 1\u00aa definici\u00f3n de apocalipticos\napocalipticos :: [Integer]\napocalipticos = [n | n <- [1..], esApocaliptico n]\n\n-- 2\u00aa definici\u00f3n de apocalipticos\napocalipticos2 :: [Integer]\napocalipticos2 = filter esApocaliptico [1..]\n\n-- 1\u00aa definici\u00f3n de posicionApocaliptica\nposicionApocaliptica :: Integer -> Maybe Int\nposicionApocaliptica n\n  | y == n    = Just (length xs)\n  | otherwise = Nothing\n  where (xs,y:_) = span (<n) apocalipticos\n\n-- 2\u00aa definici\u00f3n de posicionApocaliptica\nposicionApocaliptica2 :: Integer -> Maybe Int\nposicionApocaliptica2 n\n  | esApocaliptico n = elemIndex n apocalipticos\n  | otherwise        = Nothing\n<\/pre>\n<h4>Pensamiento<\/h4>\n<blockquote><p>\nA vosotros no os importe pensar lo que hab\u00e9is le\u00eddo ochenta veces y o\u00eddo<br \/>\nquinientas, porque no es lo mismo pensar que haber le\u00eddo.<\/p>\n<p>Antonio Machado\n<\/p><\/blockquote>\n","protected":false},"excerpt":{"rendered":"<p>Un n\u00famero natural n es apocal\u00edptico si 2^n contiene la secuencia 666. Por ejemplo, 157 es apocal\u00edptico porque 2^157 es 182687704666362864775460604089535377456991567872 que contiene la secuencia 666. Definir las funciones esApocaliptico :: Integer -> Bool apocalipticos :: [Integer] posicionApocaliptica :: Integer -> Maybe Int tales que (esApocaliptico n) se verifica si n es un n\u00famero apocal\u00edptico&#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":[5],"tags":[8,420,38,316,28,11,33,60],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/4490"}],"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=4490"}],"version-history":[{"count":5,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/4490\/revisions"}],"predecessor-version":[{"id":4527,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/4490\/revisions\/4527"}],"wp:attachment":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/media?parent=4490"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/categories?post=4490"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/tags?post=4490"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}