{"id":2642,"date":"2016-12-01T06:00:27","date_gmt":"2016-12-01T04:00:27","guid":{"rendered":"http:\/\/www.glc.us.es\/~jalonso\/exercitium\/?p=2642"},"modified":"2016-12-08T08:01:28","modified_gmt":"2016-12-08T06:01:28","slug":"sumas-de-posiciones-pares-e-impares","status":"publish","type":"post","link":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/sumas-de-posiciones-pares-e-impares\/","title":{"rendered":"Sumas de posiciones pares e impares"},"content":{"rendered":"<p>Definir la funci\u00f3n<\/p>\n<pre lang=\"text\">\n   sumasParesImpares :: [Integer] -> (Integer,Integer)\n<\/pre>\n<p>tal que (sumasParesImpares) xs es el par formado por la suma de los elementos de xs en posiciones pares y por la suma de los elementos de xs en posiciones impares. Por ejemplo,<\/p>\n<pre lang=\"text\">\n   sumasParesImpares []         ==  (0,0)\n   sumasParesImpares [3]        ==  (3,0)\n   sumasParesImpares [3,2]      ==  (3,2)\n   sumasParesImpares [3,2,1]    ==  (4,2)\n   sumasParesImpares [3,2,1,5]  ==  (4,7)\n   sumasParesImpares [1..10^7]  ==  (25000000000000,25000005000000)\n<\/pre>\n<h4>Soluciones<\/h4>\n<pre lang=\"haskell\">\n-- 1\u00aa soluci\u00f3n\nsumasParesImpares1 :: [Integer] -> (Integer,Integer)\nsumasParesImpares1 xs =\n  (sum [x | (x,n) <- xns, even n],\n   sum [x | (x,n) <- xns, odd n])\n  where xns = zip xs [0..]\n\n-- 2\u00aa soluci\u00f3n\nsumasParesImpares2 :: [Integer] -> (Integer,Integer)\nsumasParesImpares2 xs = aux xs (0,0)\n  where aux (x1:x2:xs) (a,b) = aux xs (x1+a,x2+b)\n        aux [x]        (a,b) = (x+a,b)\n        aux []         (a,b) = (a,b)\n  \n-- Comparaci\u00f3n de eficiencia\n--    \u03bb> sumasParesImpares1 [1..10^6]\n--    (250000000000,250000500000)\n--    (4.48 secs, 731,994,904 bytes)\n--    \u03bb> sumasParesImpares2 [1..10^6]\n--    (250000000000,250000500000)\n--    (1.78 secs, 235,663,400 bytes)\n<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>Definir la funci\u00f3n sumasParesImpares :: [Integer] -> (Integer,Integer) tal que (sumasParesImpares) xs es el par formado por la suma de los elementos de xs en posiciones pares y por la suma de los elementos de xs en posiciones impares. Por ejemplo, sumasParesImpares [] == (0,0) sumasParesImpares [3] == (3,0) sumasParesImpares [3,2] == (3,2) sumasParesImpares [3,2,1]&#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":[8,91,92,6,40,9],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/2642"}],"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=2642"}],"version-history":[{"count":4,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/2642\/revisions"}],"predecessor-version":[{"id":2670,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/2642\/revisions\/2670"}],"wp:attachment":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/media?parent=2642"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/categories?post=2642"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/tags?post=2642"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}