{"id":7910,"date":"2023-02-22T06:00:40","date_gmt":"2023-02-22T04:00:40","guid":{"rendered":"http:\/\/www.glc.us.es\/~jalonso\/exercitium\/?p=7910"},"modified":"2023-01-27T13:05:42","modified_gmt":"2023-01-27T11:05:42","slug":"22-feb-23","status":"publish","type":"post","link":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/22-feb-23\/","title":{"rendered":"TAD de las colas: Reconocimiento de prefijos de colas"},"content":{"rendered":"<p>Utilizando el <a href=\"https:\/\/bit.ly\/3QWTsRL\">tipo abstracto de datos de las colas<\/a>, definir la funci\u00f3n<\/p>\n<pre lang=\"text\">\n   prefijoCola :: Eq a => Cola a -> Cola a -> Bool\n<\/pre>\n<p>tal que <code>prefijoCola c1 c2<\/code> se verifica si la cola <code>c1<\/code> es justamente un prefijo de la cola <code>c2<\/code>. Por ejemplo,<\/p>\n<pre lang=\"text\">\n   \u03bb> ej1 = inserta 4 (inserta 2 vacia)\n   \u03bb> ej2 = inserta 5 (inserta 4 (inserta 2 vacia))\n   \u03bb> ej3 = inserta 5 (inserta 2 (inserta 4 vacia))\n   \u03bb> prefijoCola ej1 ej2\n   True\n   \u03bb> prefijoCola ej1 ej3\n   False\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\">\nimport TAD.Cola (Cola, vacia, inserta, esVacia, primero, resto)\nimport Transformaciones_colas_listas (colaAlista)\nimport Data.List (isPrefixOf)\nimport Test.QuickCheck\n\n-- 1\u00aa soluci\u00f3n\n-- ===========\n\nprefijoCola :: Eq a => Cola a -> Cola a -> Bool\nprefijoCola c1 c2\n  | esVacia c1 = True\n  | esVacia c2 = False\n  | otherwise  = primero c1 == primero c2 &&\n                 prefijoCola (resto c1) (resto c2)\n\n-- 2\u00aa soluci\u00f3n\n-- ===========\n\nprefijoCola2 :: Eq a => Cola a -> Cola a -> Bool\nprefijoCola2 c1 c2 =\n  colaAlista c1 `isPrefixOf` colaAlista c2\n\n-- La funci\u00f3n colaAlista est\u00e1 definida en el ejercicio\n-- \"Transformaciones entre colas y listas\" que se encuentra en\n-- https:\/\/bit.ly\/3Xv0oIt\n\n-- Comprobaci\u00f3n de equivalencia\n-- ============================\n\n-- La propiedad es\nprop_prefijoCola :: Cola Int -> Cola Int -> Bool\nprop_prefijoCola c1 c2 =\n  prefijoCola c1 c2 == prefijoCola2 c1 c2\n\n-- La comprobaci\u00f3n es\n--    \u03bb> quickCheck prop_prefijoCola\n--    +++ OK, passed 100 tests.\n<\/pre>\n<p><a name=\"python\"><\/a><br \/>\n<b>Soluciones en Python<\/b><\/p>\n<pre lang=\"python\">\nfrom copy import deepcopy\nfrom typing import TypeVar\n\nfrom hypothesis import given\n\nfrom src.TAD.cola import (Cola, colaAleatoria, esVacia, inserta, primero,\n                          resto, vacia)\nfrom src.transformaciones_colas_listas import colaAlista\n\nA = TypeVar('A')\n\n# 1\u00aa soluci\u00f3n\n# ===========\n\ndef prefijoCola(c1: Cola[A], c2: Cola[A]) -> bool:\n    if esVacia(c1):\n        return True\n    if esVacia(c2):\n        return False\n    return primero(c1) == primero(c2) and prefijoCola(resto(c1), resto(c2))\n\n# 2\u00aa soluci\u00f3n\n# ===========\n\ndef esPrefijoLista(xs: list[A], ys: list[A]) -> bool:\n    return ys[:len(xs)] == xs\n\ndef prefijoCola2(c1: Cola[A], c2: Cola[A]) -> bool:\n    return esPrefijoLista(colaAlista(c1), colaAlista(c2))\n\n# La funci\u00f3n colaAlista est\u00e1 definida en el ejercicio\n# \"Transformaciones entre colas y listas\" que se encuentra en\n# https:\/\/bit.ly\/3Xv0oIt\n\n# 3\u00aa soluci\u00f3n\n# ===========\n\ndef prefijoCola3Aux(c1: Cola[A], c2: Cola[A]) -> bool:\n    if c1.esVacia():\n        return True\n    if c2.esVacia():\n        return False\n    cc1 = c1.primero()\n    c1.resto()\n    cc2 = c2.primero()\n    c2.resto()\n    return cc1 == cc2 and prefijoCola3(c1, c2)\n\ndef prefijoCola3(c1: Cola[A], c2: Cola[A]) -> bool:\n    q1 = deepcopy(c1)\n    q2 = deepcopy(c2)\n    return prefijoCola3Aux(q1, q2)\n\n# 4\u00aa soluci\u00f3n\n# ===========\n\ndef prefijoCola4Aux(c1: Cola[A], c2: Cola[A]) -> bool:\n    while not c2.esVacia() and not c1.esVacia():\n        if c1.primero() != c2.primero():\n            return False\n        c1.resto()\n        c2.resto()\n    return c1.esVacia()\n\ndef prefijoCola4(c1: Cola[A], c2: Cola[A]) -> bool:\n    q1 = deepcopy(c1)\n    q2 = deepcopy(c2)\n    return prefijoCola4Aux(q1, q2)\n\n# Comprobaci\u00f3n de equivalencia de las definiciones\n# ================================================\n\n# La propiedad es\n@given(c1=colaAleatoria(), c2=colaAleatoria())\ndef test_prefijoCola(c1: Cola[int], c2: Cola[int]) -> None:\n    r = prefijoCola(c1, c2)\n    assert prefijoCola2(c1, c2) == r\n    assert prefijoCola3(c1, c2) == r\n    assert prefijoCola4(c1, c2) == r\n\n# La comprobaci\u00f3n es\n#    src> poetry run pytest -q prefijoCola.py\n#    1 passed in 0.29s\n<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>Utilizando el tipo abstracto de datos de las colas, definir la funci\u00f3n prefijoCola :: Eq a => Cola a -> Cola a -> Bool tal que prefijoCola c1 c2 se verifica si la cola c1 es justamente un prefijo de la cola c2. Por ejemplo, \u03bb> ej1 = inserta 4 (inserta 2 vacia) \u03bb> ej2&#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":[515,585],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/7910"}],"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=7910"}],"version-history":[{"count":1,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/7910\/revisions"}],"predecessor-version":[{"id":7911,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/7910\/revisions\/7911"}],"wp:attachment":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/media?parent=7910"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/categories?post=7910"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/tags?post=7910"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}