{"id":7779,"date":"2023-01-12T06:00:23","date_gmt":"2023-01-12T04:00:23","guid":{"rendered":"http:\/\/www.glc.us.es\/~jalonso\/exercitium\/?p=7779"},"modified":"2022-12-30T14:59:19","modified_gmt":"2022-12-30T12:59:19","slug":"12-ene-23","status":"publish","type":"post","link":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/12-ene-23\/","title":{"rendered":"N\u00famero de sumas en una expresi\u00f3n aritm\u00e9tica"},"content":{"rendered":"<p>Las expresiones aritm\u00e9ticas con variables pueden representarse usando el siguiente tipo de datos<\/p>\n<pre lang=\"text\">\n   data Expr = C Int\n             | V Char\n             | S Expr Expr\n             | P Expr Expr\n<\/pre>\n<p>Por ejemplo, la expresi\u00f3n <code>2\u00b7(a+5)<\/code> se representa por<\/p>\n<pre lang=\"text\">\n   P (C 2) (S (V 'a') (C 5))\n<\/pre>\n<p>Definir la funci\u00f3n<\/p>\n<pre lang=\"text\">\n   sumas :: Expr -> Int\n<\/pre>\n<p>tal que <code>sumas e<\/code> es el n\u00famero de sumas en la expresi\u00f3n <code>e<\/code>. Por ejemplo,<\/p>\n<pre lang=\"text\">\n   sumas (P (V 'z') (S (C 3) (V 'x')))  ==  1\n   sumas (S (V 'z') (S (C 3) (V 'x')))  ==  2\n   sumas (P (V 'z') (P (C 3) (V 'x')))  ==  0\n<\/pre>\n<p><b>Soluciones<\/b><\/p>\n<p>A continuaci\u00f3n se muestran las <a href=\"#haskell\">soluciones en Haskell<\/a> y las <a href=\"#python\">soluciones en Python<\/a>.<\/p>\n<p><a name=\"haskell\"><\/a><br \/>\n<b>Soluciones en Haskell<\/b><\/p>\n<pre lang=\"haskell\">\ndata Expr = C Int\n          | V Char\n          | S Expr Expr\n          | P Expr Expr\n\nsumas :: Expr -> Int\nsumas (V _)   = 0\nsumas (C _)   = 0\nsumas (S x y) = 1 + sumas x + sumas y\nsumas (P x y) = sumas x + sumas y\n<\/pre>\n<p><a name=\"python\"><\/a><br \/>\n<b>Soluciones en Python<\/b><\/p>\n<pre lang=\"python\">\nfrom dataclasses import dataclass\n\n\n@dataclass\nclass Expr:\n    pass\n\n@dataclass\nclass C(Expr):\n    x: int\n\n@dataclass\nclass V(Expr):\n    x: str\n\n@dataclass\nclass S(Expr):\n    x: Expr\n    y: Expr\n\n@dataclass\nclass P(Expr):\n    x: Expr\n    y: Expr\n\ndef sumas(e: Expr) -> int:\n    match e:\n        case C(a):\n            return 0\n        case V(x):\n            return 0\n        case S(e1, e2):\n            return 1 + sumas(e1) + sumas(e2)\n        case P(e1, e2):\n            return sumas(e1) + sumas(e2)\n    assert False\n<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>Las expresiones aritm\u00e9ticas con variables pueden representarse usando el siguiente tipo de datos data Expr = C Int | V Char | S Expr Expr | P Expr Expr Por ejemplo, la expresi\u00f3n 2\u00b7(a+5) se representa por P (C 2) (S (V &#8216;a&#8217;) (C 5)) Definir la funci\u00f3n sumas :: Expr -> 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":[581],"tags":[582],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/7779"}],"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=7779"}],"version-history":[{"count":1,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/7779\/revisions"}],"predecessor-version":[{"id":7780,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/7779\/revisions\/7780"}],"wp:attachment":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/media?parent=7779"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/categories?post=7779"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/tags?post=7779"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}