{"id":1133,"date":"2015-02-26T06:00:40","date_gmt":"2015-02-26T04:00:40","guid":{"rendered":"http:\/\/www.glc.us.es\/~jalonso\/exercitium\/?p=1133"},"modified":"2016-05-01T19:28:32","modified_gmt":"2016-05-01T17:28:32","slug":"mayor-diferencia-progresiva","status":"publish","type":"post","link":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/mayor-diferencia-progresiva\/","title":{"rendered":"Mayor diferencia progresiva"},"content":{"rendered":"<p>La diferencia progresiva entre dos elementos de una lista es la resta entre el que ocupa la mayor posici\u00f3n y la menor. Por ejemplo, en la lista [1,5,8,2,9] la diferencia entre los elementos 5 y 8 es 3 y entre 5 y 2 es -3.<\/p>\n<p>Definir la funci\u00f3n<\/p>\n<pre lang=\"text\">\n   mayorDiferencia :: [Int] -> Int\n<\/pre>\n<p>tal que (mayorDiferencia xs) es la mayor diferencia progresiva entre los elementos de xs. Por ejemplo,<\/p>\n<pre lang=\"text\">\n   mayorDiferencia [1,5,8,2,9]  ==  8\n   mayorDiferencia [9,5,8,2,1]  ==  3\n   mayorDiferencia [7,2,6]      ==  4\n   mayorDiferencia [3,2,1]      ==  0\n   mayorDiferencia [1..10^7]    ==  9999999\n<\/pre>\n<h4>Soluciones<\/h4>\n<pre lang=\"haskell\">\nimport Data.List (inits)\n\n-- 1\u00aa definici\u00f3n (por recursi\u00f3n):\nmayorDiferencia :: [Int] -> Int\nmayorDiferencia ([_])  = 0\nmayorDiferencia (x:xs) = \n    max (maximum [y-x | y <- xs]) (mayorDiferencia xs) \n\n-- 2\u00aa definici\u00f3n (por comprensi\u00f3n)\nmayorDiferencia2 :: [Int] -> Int\nmayorDiferencia2 xs = \n    maximum [x-y | (x,y) <- zip xs (map minimum (tail (inits xs)))]\n\n-- 3\u00aa definici\u00f3n:\nmayorDiferencia3 :: [Int] -> Int\nmayorDiferencia3 xs = maximum (zipWith (-) xs (scanl1 min xs))\n\n-- 4\u00aa definici\u00f3n:\nmayorDiferencia4 :: [Int] -> Int\nmayorDiferencia4 xs = maximum . zipWith (-) xs $ scanl1 min xs\n\n-- Comparaci\u00f3n de eficiencia\n--    ghci> mayorDiferencia [1..3000]\n--    2999\n--    (3.43 secs, 943439560 bytes)\n--    \n--    ghci> mayorDiferencia2 [1..3000]\n--    2999\n--    (3.38 secs, 978359192 bytes)\n--    \n--    ghci> mayorDiferencia3 [1..3000]\n--    2999\n--    (0.01 secs, 2877960 bytes)\n--    \n--    ghci> mayorDiferencia4 [1..3000]\n--    2999\n--    (0.01 secs, 2062616 bytes)\n<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>La diferencia progresiva entre dos elementos de una lista es la resta entre el que ocupa la mayor posici\u00f3n y la menor. Por ejemplo, en la lista [1,5,8,2,9] la diferencia entre los elementos 5 y 8 es 3 y entre 5 y 2 es -3. Definir la funci\u00f3n mayorDiferencia :: [Int] -> Int tal que&#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":[8,74,83,15,6,252,45,9,76],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/1133"}],"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=1133"}],"version-history":[{"count":4,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/1133\/revisions"}],"predecessor-version":[{"id":1166,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/1133\/revisions\/1166"}],"wp:attachment":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/media?parent=1133"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/categories?post=1133"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/tags?post=1133"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}