{"id":4395,"date":"2018-12-11T06:00:40","date_gmt":"2018-12-11T04:00:40","guid":{"rendered":"http:\/\/www.glc.us.es\/~jalonso\/exercitium\/?p=4395"},"modified":"2019-01-17T15:43:43","modified_gmt":"2019-01-17T13:43:43","slug":"arbol-de-computacion-de-fibonacci","status":"publish","type":"post","link":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/arbol-de-computacion-de-fibonacci\/","title":{"rendered":"\u00c1rbol de computaci\u00f3n de Fibonacci"},"content":{"rendered":"<p>La sucesi\u00f3n de Fibonacci es<\/p>\n<pre lang=\"text\">\n   0,1,1,2,3,5,8,13,21,34,55,89,144,233,377,610,987,1597,2584,...\n<\/pre>\n<p>cuyos dos primeros t\u00e9rminos son 0 y 1 y los restantentes se obtienen sumando los dos anteriores.<\/p>\n<p>El \u00e1rbol de computaci\u00f3n de su 5\u00ba t\u00e9rmino es<\/p>\n<pre lang=\"text\">\n                 5\n                \/ \\\n               \/   \\\n              \/     \\\n             \/       \\\n            \/         \\\n           3           2  \n          \/ \\         \/ \\ \n         \/   \\       1   1\n        2     1     \/ \\   \n       \/ \\   \/ \\   1   0  \n      1   1 1   0\n     \/ \\ \n    1   0  \n<\/pre>\n<p>que, usando los \u00e1rboles definidos por<\/p>\n<pre lang=\"text\">\n   data Arbol = H Int\n              | N Int Arbol Arbol\n     deriving (Eq, Show)\n<\/pre>\n<p>se puede representar por<\/p>\n<pre lang=\"text\">\n   N 5              \n     (N 3           \n        (N 2        \n           (N 1 (H 1) (H 0))\n           (H 1))   \n        (N 1 (H 1) (H 0)))  \n     (N 2           \n        (N 1 (H 1) (H 0))   \n        (H 1))     \n<\/pre>\n<p>Definir las funciones<\/p>\n<pre lang=\"text\">\n   arbolFib           :: Int -> Arbol\n   nElementosArbolFib :: Int -> Int\n<\/pre>\n<p>tales que<\/p>\n<ul>\n<li>(arbolFib n) es el \u00e1rbol de computaci\u00f3n del n-\u00e9simo t\u00e9rmino de la sucesi\u00f3n de Fibonacci. Por ejemplo,<\/li>\n<\/ul>\n<pre lang=\"text\">\n     \u03bb> arbolFib 5\n     N 5              \n       (N 3           \n          (N 2        \n             (N 1 (H 1) (H 0))\n             (H 1))   \n          (N 1 (H 1) (H 0)))  \n       (N 2           \n          (N 1 (H 1) (H 0))   \n          (H 1))\n     \u03bb> arbolFib 6\n     N 8\n       (N 5\n          (N 3\n             (N 2\n                (N 1 (H 1) (H 0))\n                (H 1))\n             (N 1 (H 1) (H 0)))\n          (N 2\n             (N 1 (H 1) (H 0))\n             (H 1)))\n       (N 3\n          (N 2\n             (N 1 (H 1) (H 0)) (H 1))\n          (N 1 (H 1) (H 0)))\n<\/pre>\n<ul>\n<li>(nElementosArbolFib n) es el n\u00famero de elementos en el \u00e1rbol de computaci\u00f3n del n-\u00e9simo t\u00e9rmino de la sucesi\u00f3n de Fibonacci. Por ejemplo, <\/li>\n<\/ul>\n<pre lang=\"text\">\n     nElementosArbolFib 5   ==  15\n     nElementosArbolFib 6   ==  25\n     nElementosArbolFib 30  ==  2692537\n<\/pre>\n<h4>Soluciones<\/h4>\n<pre lang=\"haskell\">\ndata Arbol = H Int\n           | N Int Arbol Arbol\n  deriving (Eq, Show)\n\n-- 1\u00aa definici\u00f3n\n-- =============\n\narbolFib :: Int -> Arbol\narbolFib 0 = H 0\narbolFib 1 = H 1\narbolFib n = N (fib n) (arbolFib (n-1)) (arbolFib (n-2))\n\n-- (fib n) es el n-\u00e9simo elemento de la sucesi\u00f3n de Fibonacci. Por\n-- ejemplo,\n--    fib 5  ==  5\n--    fib 6  ==  8\nfib :: Int -> Int\nfib 0 = 0\nfib 1 = 1\nfib n = fib (n-1) + fib (n-2)\n\n-- 2\u00aa definici\u00f3n\n-- =============\n\narbolFib2 :: Int -> Arbol\narbolFib2 0 = H 0\narbolFib2 1 = H 1\narbolFib2 2 = N 1 (H 1) (H 0)\narbolFib2 3 = N 2 (N 1 (H 1) (H 0)) (H 1)\narbolFib2 n = N (a1 + a2) (N a1 i1 d1) (N a2 i2 d2)\n  where (N a1 i1 d1) = arbolFib2 (n-1)\n        (N a2 i2 d2) = arbolFib2 (n-2)\n\n-- 3\u00aa definici\u00f3n\n-- =============\n\narbolFib3 :: Int -> Arbol\narbolFib3 0 = H 0\narbolFib3 1 = H 1\narbolFib3 2 = N 1 (H 1) (H 0)\narbolFib3 3 = N 2 (N 1 (H 1) (H 0)) (H 1)\narbolFib3 n = N (a + b) i d\n  where i@(N a _ _) = arbolFib3 (n-1)\n        d@(N b _ _) = arbolFib3 (n-2)\n\n-- 1\u00aa definici\u00f3n de nElementosArbolFib\n-- ===================================\n\nnElementosArbolFib :: Int -> Int\nnElementosArbolFib = length . elementos . arbolFib3\n\n-- (elementos a) es la lista de elementos del \u00e1rbol a. Por ejemplo,\n--    \u03bb> elementos (arbolFib 5)\n--    [5,3,2,1,1,0,1,1,1,0,2,1,1,0,1]\n--    \u03bb> elementos (arbolFib 6)\n--    [8,5,3,2,1,1,0,1,1,1,0,2,1,1,0,1,3,2,1,1,0,1,1,1,0]\nelementos :: Arbol -> [Int]\nelementos (H x)     = [x]\nelementos (N x i d) = x : elementos i ++ elementos d\n\n-- 2\u00aa definici\u00f3n de nElementosArbolFib\n-- ===================================\n\nnElementosArbolFib2 :: Int -> Int\nnElementosArbolFib2 0 = 1\nnElementosArbolFib2 1 = 1\nnElementosArbolFib2 n = 1 + nElementosArbolFib2 (n-1)\n                          + nElementosArbolFib2 (n-2)\n<\/pre>\n<h4>Pensamiento<\/h4>\n<blockquote><p>\nToda visi\u00f3n requiere distancia.<\/p>\n<p>Antonio Machado\n<\/p><\/blockquote>\n","protected":false},"excerpt":{"rendered":"<p>La sucesi\u00f3n de Fibonacci es 0,1,1,2,3,5,8,13,21,34,55,89,144,233,377,610,987,1597,2584,&#8230; cuyos dos primeros t\u00e9rminos son 0 y 1 y los restantentes se obtienen sumando los dos anteriores. El \u00e1rbol de computaci\u00f3n de su 5\u00ba t\u00e9rmino es 5 \/ \\ \/ \\ \/ \\ \/ \\ \/ \\ 3 2 \/ \\ \/ \\ \/ \\ 1 1 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":[4],"tags":[269,28,6],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/4395"}],"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=4395"}],"version-history":[{"count":3,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/4395\/revisions"}],"predecessor-version":[{"id":4578,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/4395\/revisions\/4578"}],"wp:attachment":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/media?parent=4395"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/categories?post=4395"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/tags?post=4395"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}