{"id":1016,"date":"2015-01-29T06:00:09","date_gmt":"2015-01-29T04:00:09","guid":{"rendered":"http:\/\/www.glc.us.es\/~jalonso\/exercitium\/?p=1016"},"modified":"2022-03-26T12:13:30","modified_gmt":"2022-03-26T10:13:30","slug":"posicion-del-primer-falso-en-un-vector","status":"publish","type":"post","link":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/posicion-del-primer-falso-en-un-vector\/","title":{"rendered":"Posici\u00f3n del primer falso en un vector"},"content":{"rendered":"<h4>Excercitium<\/h4>\n<p>Definir la funci\u00f3n<\/p>\n<pre lang=\"text\">\n   posicion :: Array Int Bool -> Maybe Int\n<\/pre>\n<p>tal que (posicion v) es la menor posici\u00f3n del vector de booleanos v cuyo valor es falso y es Nothing si todos los valores son verdaderos. Por ejemplo,<\/p>\n<pre lang=\"text\">\n   posicion (listArray (0,4) [True,True,False,True,False]) == Just 2\n   posicion (listArray (0,4) [i <= 2 | i <- [0..4]])       == Just 3\n   posicion (listArray (0,4) [i <= 7 | i <- [0..4]])       == Nothing\n<\/pre>\n<h4>Soluciones<\/h4>\n<pre lang=\"haskell\">\nimport Data.Array \n\n-- 1\u00aa definici\u00f3n:\nposicion :: Array Int Bool -> Maybe Int\nposicion v | p > n     = Nothing\n           | otherwise = Just p\n    where p = (length . takeWhile id . elems) v\n          (_,n) = bounds v \n\n-- 2\u00aa posici\u00f3n:\nposicion2 :: Array Int Bool -> Maybe Int\nposicion2 v | null xs   = Nothing\n            | otherwise = Just (head xs)\n    where xs = [i | i <- indices v, v!i]\n<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>Excercitium Definir la funci\u00f3n posicion :: Array Int Bool -> Maybe Int tal que (posicion v) es la menor posici\u00f3n del vector de booleanos v cuyo valor es falso y es Nothing si todos los valores son verdaderos. Por ejemplo, posicion (listArray (0,4) [True,True,False,True,False]) == Just 2 posicion (listArray (0,4) [i<\/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":[43,8,500,245,71,63,82,28,141,11,34,53],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/1016"}],"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=1016"}],"version-history":[{"count":3,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/1016\/revisions"}],"predecessor-version":[{"id":1018,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/1016\/revisions\/1018"}],"wp:attachment":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/media?parent=1016"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/categories?post=1016"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/tags?post=1016"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}