{"id":4010,"date":"2018-04-26T06:00:54","date_gmt":"2018-04-26T04:00:54","guid":{"rendered":"http:\/\/www.glc.us.es\/~jalonso\/exercitium\/?p=4010"},"modified":"2018-05-07T21:48:29","modified_gmt":"2018-05-07T19:48:29","slug":"diccionario-inverso","status":"publish","type":"post","link":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/diccionario-inverso\/","title":{"rendered":"Diccionario inverso"},"content":{"rendered":"<p>El inverso de un diccionario d es el diccionario que a cada valor x le asigna la lista de claves cuyo valor en d es x. Por ejemplo, el inverso de<\/p>\n<pre lang=\"text\">\n   [(\"a\",3),(\"b\",2),(\"c\",3),(\"d\",2),(\"e\",1)])\n<\/pre>\n<p>es<\/p>\n<pre lang=\"text\">\n   [(1,[\"e\"]),(2,[\"d\",\"b\"]),(3,[\"c\",\"a\"])]\n<\/pre>\n<p>Definir la funci\u00f3n<\/p>\n<pre lang=\"text\">\n   inverso :: (Ord k, Ord v) => Map k v -> Map v [k]\n<\/pre>\n<p>tal que (inverso d) es el inverso del diccionario d. Por ejemplo,<\/p>\n<pre lang=\"text\">\n   \u03bb> inverso (fromList [(\"a\",3),(\"b\",2),(\"c\",3),(\"d\",2),(\"e\",1)])\n   fromList [(1,[\"e\"]),(2,[\"d\",\"b\"]),(3,[\"c\",\"a\"])]\n   \u03bb> inverso (fromList [(x,x^2) | x <- [-3,-2..3]])\n   fromList [(0,[0]),(1,[1,-1]),(4,[2,-2]),(9,[3,-3])]\n<\/pre>\n<h4>Soluciones<\/h4>\n<pre lang=\"haskell\">\nimport Data.Map ( Map\n                , assocs\n                , deleteFindMin\n                , empty\n                , fromList\n                , fromListWith\n                , insertWith\n                )\nimport qualified Data.Map as M \n\n\n-- 1\u00aa definici\u00f3n\ninverso :: (Ord k, Ord v) => Map k v -> Map v [k]\ninverso d = fromListWith (++) [(y,[x]) | (x,y) <- assocs d]\n\n-- 2\u00aa definici\u00f3n\ninverso2 :: (Ord k, Ord v) => Map k v -> Map v [k]\ninverso2 d\n  | M.null d  = empty\n  | otherwise = insertWith (++) y [x] (inverso2 e)\n  where ((x,y),e) = deleteFindMin d\n<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>El inverso de un diccionario d es el diccionario que a cada valor x le asigna la lista de claves cuyo valor en d es x. Por ejemplo, el inverso de [(\u00aba\u00bb,3),(\u00abb\u00bb,2),(\u00abc\u00bb,3),(\u00abd\u00bb,2),(\u00abe\u00bb,1)]) es [(1,[\u00abe\u00bb]),(2,[\u00abd\u00bb,\u00bbb\u00bb]),(3,[\u00abc\u00bb,\u00bba\u00bb])] Definir la funci\u00f3n inverso :: (Ord k, Ord v) => Map k v -> Map v [k] tal que (inverso d)&#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":[55,8,290,451],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/4010"}],"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=4010"}],"version-history":[{"count":2,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/4010\/revisions"}],"predecessor-version":[{"id":4040,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/4010\/revisions\/4040"}],"wp:attachment":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/media?parent=4010"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/categories?post=4010"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/tags?post=4010"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}