{"id":7817,"date":"2023-01-26T06:00:30","date_gmt":"2023-01-26T04:00:30","guid":{"rendered":"http:\/\/www.glc.us.es\/~jalonso\/exercitium\/?p=7817"},"modified":"2023-01-22T17:29:43","modified_gmt":"2023-01-22T15:29:43","slug":"26-ene-23","status":"publish","type":"post","link":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/26-ene-23\/","title":{"rendered":"TAD de las pilas: Pertenencia a una pila"},"content":{"rendered":"<p>Utilizando el <a href=\"https:\/\/bit.ly\/3GTToyK\">tipo abstracto de datos de las pilas<\/a>, definir la funci\u00f3n<\/p>\n<pre lang=\"text\">\n   pertenecePila :: Eq a => a -> Pila a -> Bool\n<\/pre>\n<p>tal que <code>pertenecePila x p<\/code> se verifica si <code>x<\/code> es un elemento de la pila <code>p<\/code>. Por ejemplo,<\/p>\n<pre lang=\"text\">\n   pertenecePila 2 (apila 5 (apila 2 (apila 3 vacia))) == True\n   pertenecePila 4 (apila 5 (apila 2 (apila 3 vacia))) == 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.Pila (Pila, vacia, apila, esVacia, cima, desapila)\nimport Transformaciones_pilas_listas (pilaAlista)\nimport Test.QuickCheck\n\n-- 1\u00aa soluci\u00f3n\n-- ===========\n\npertenecePila :: Eq a => a -> Pila a -> Bool\npertenecePila x p\n  | esVacia p  = False\n  | otherwise  = x == cp || pertenecePila x dp\n  where cp = cima p\n        dp = desapila p\n\n-- 2\u00aa soluci\u00f3n\n-- ===========\n\n-- Se usar\u00e1 la funci\u00f3n pilaAlista del ejercicio\n-- \"Transformaciones entre pilas y listas\" que se encuentra en\n-- https:\/\/bit.ly\/3ZHewQ8\n\npertenecePila2 :: Eq a => a -> Pila a -> Bool\npertenecePila2 x p =\n  x `elem` pilaAlista p\n\n-- Comprobaci\u00f3n de equivalencia\n-- ============================\n\n-- La propiedad es\nprop_pertenecePila :: Int -> Pila Int -> Bool\nprop_pertenecePila x p =\n  pertenecePila x p == pertenecePila2 x p\n\n-- La comprobaci\u00f3n es\n--    \u03bb> quickCheck prop_pertenecePila\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\nfrom hypothesis import strategies as st\n\nfrom src.TAD.pila import (Pila, apila, cima, desapila, esVacia, pilaAleatoria,\n                          vacia)\nfrom src.transformaciones_pilas_listas import pilaAlista\n\nA = TypeVar('A')\n\n# 1\u00aa soluci\u00f3n\n# ===========\n\ndef pertenecePila(x: A, p: Pila[A]) -> bool:\n    if esVacia(p):\n        return False\n    cp = cima(p)\n    dp = desapila(p)\n    return x == cp or pertenecePila(x, dp)\n\n# 2\u00aa soluci\u00f3n\n# ===========\n\n# Se usar\u00e1 la funci\u00f3n pilaAlista del ejercicio\n# \"Transformaciones entre pilas y listas\" que se encuentra en\n# https:\/\/bit.ly\/3ZHewQ8\n\ndef pertenecePila2(x: A, p: Pila[A]) -> bool:\n    return x in pilaAlista(p)\n\n# 3\u00aa soluci\u00f3n\n# ===========\n\ndef pertenecePila3Aux(x: A, p: Pila[A]) -> bool:\n    if p.esVacia():\n        return False\n    cp = p.cima()\n    p.desapila()\n    return x == cp or pertenecePila3Aux(x, p)\n\ndef pertenecePila3(x: A, p: Pila[A]) -> bool:\n    p1 = deepcopy(p)\n    return pertenecePila3Aux(x, p1)\n\n# 4\u00aa soluci\u00f3n\n# ===========\n\ndef pertenecePila4Aux(x: A, p: Pila[A]) -> bool:\n    while not p.esVacia():\n        cp = p.cima()\n        p.desapila()\n        if x == cp:\n            return True\n    return False\n\ndef pertenecePila4(x: A, p: Pila[A]) -> bool:\n    p1 = deepcopy(p)\n    return pertenecePila4Aux(x, p1)\n\n# Comprobaci\u00f3n de equivalencia de las definiciones\n# ================================================\n\n# La propiedad es\n@given(x=st.integers(), p=pilaAleatoria())\ndef test_pertenecePila(x: int, p: Pila[int]) -> None:\n    r = pertenecePila(x, p)\n    assert pertenecePila2(x, p) == r\n    assert pertenecePila3(x, p) == r\n    assert pertenecePila4(x, p) == r\n\n# La comprobaci\u00f3n es\n#    src> poetry run pytest -q pertenecePila.py\n#    1 passed in 0.37s\n<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>Utilizando el tipo abstracto de datos de las pilas, definir la funci\u00f3n pertenecePila :: Eq a => a -> Pila a -> Bool tal que pertenecePila x p se verifica si x es un elemento de la pila p. Por ejemplo, pertenecePila 2 (apila 5 (apila 2 (apila 3 vacia))) == True pertenecePila 4 (apila&#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":[586,357],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/7817"}],"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=7817"}],"version-history":[{"count":4,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/7817\/revisions"}],"predecessor-version":[{"id":7869,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/7817\/revisions\/7869"}],"wp:attachment":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/media?parent=7817"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/categories?post=7817"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/tags?post=7817"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}