{"id":4536,"date":"2019-01-14T06:00:16","date_gmt":"2019-01-14T04:00:16","guid":{"rendered":"http:\/\/www.glc.us.es\/~jalonso\/exercitium\/?p=4536"},"modified":"2019-01-21T08:14:32","modified_gmt":"2019-01-21T06:14:32","slug":"ofertas-3-por-2","status":"publish","type":"post","link":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/ofertas-3-por-2\/","title":{"rendered":"Ofertas 3 por 2"},"content":{"rendered":"<p>En una tienda tiene la \u00aboferta 3 por 2\u00bb de forma que cada cliente que elige 3 art\u00edculos obtiene el m\u00e1s barato de forma gratuita. Por ejemplo, si los precios de los art\u00edculos elegidos por un cliente son 10, 2, 4, 5 euros pagar\u00e1 19 euros si agrupa los art\u00edculos en (10,2,4) y (5) o pagar\u00e1 17 si lo agupa en (5,10,4) y (2).<\/p>\n<p>Definir la funci\u00f3n<\/p>\n<pre lang=\"text\"> \n   minimoConOferta :: [Int] -> Int\n<\/pre>\n<p>tal que (minimoConOferta xs) es lo m\u00ednimo que pagar\u00e1 el cliente si los precios de la compra son xs; es decir, lo que pagar\u00e1 agrupando los art\u00edculos de forma \u00f3ptima para aplicar la oferta 3 por 2. Por ejemplo,<\/p>\n<pre lang=\"text\"> \n   minimoConOferta [10,2,4,5]     ==  17\n   minimoConOferta [3,2,3,2]      ==  8\n   minimoConOferta [6,4,5,5,5,5]  ==  21\n<\/pre>\n<h4>Soluciones<\/h4>\n<pre lang=\"haskell\">\nimport Data.List ( sort\n                 , sortOn)\nimport Data.Ord  ( Down(..))\n\n-- 1\u00aa soluci\u00f3n\n-- ===========\n\nminimoConOferta :: [Int] -> Int\nminimoConOferta xs = sum (sinTerceros (reverse (sort xs)))\n\nsinTerceros :: [a] -> [a]\nsinTerceros []         = []\nsinTerceros [x]        = [x]\nsinTerceros [x,y]      = [x,y]\nsinTerceros (x:y:_:zs) = x : y : sinTerceros zs\n\n-- 2\u00aa soluci\u00f3n\n-- ===========\n\nminimoConOferta2 :: [Int] -> Int\nminimoConOferta2 = sum . sinTerceros . reverse . sort\n\n-- 3\u00aa soluci\u00f3n\n-- ===========\n\nminimoConOferta3 :: [Int] -> Int\nminimoConOferta3 = sum . sinTerceros . sortOn Down\n\n-- 4\u00aa soluci\u00f3n\n-- ===========\n\nminimoConOferta4 :: [Int] -> Int\nminimoConOferta4 xs = aux (reverse (sort xs)) 0\n  where aux (a:b:_:ds) n = aux ds (a+b+n)\n        aux as         n = n + sum as \n\n-- 5\u00aa soluci\u00f3n\n-- ===========\n\nminimoConOferta5 :: [Int] -> Int\nminimoConOferta5 xs = aux (sortOn Down xs) 0\n  where aux (a:b:_:ds) n = aux ds (a+b+n)\n        aux as         n = n + sum as \n<\/pre>\n<h4>Pensamiento<\/h4>\n<blockquote><p>\nDespacito y buena letra:<br \/>\nel hacer las cosas bien<br \/>\nimporta m\u00e1s que el hacerlas.<\/p>\n<p>Antonio Machado\n<\/p><\/blockquote>\n","protected":false},"excerpt":{"rendered":"<p>En una tienda tiene la \u00aboferta 3 por 2\u00bb de forma que cada cliente que elige 3 art\u00edculos obtiene el m\u00e1s barato de forma gratuita. Por ejemplo, si los precios de los art\u00edculos elegidos por un cliente son 10, 2, 4, 5 euros pagar\u00e1 19 euros si agrupa los art\u00edculos en (10,2,4) y (5) o&#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":[6,32,14,40],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/4536"}],"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=4536"}],"version-history":[{"count":4,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/4536\/revisions"}],"predecessor-version":[{"id":4610,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/4536\/revisions\/4610"}],"wp:attachment":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/media?parent=4536"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/categories?post=4536"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/tags?post=4536"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}