{"id":7503,"date":"2022-11-08T06:00:41","date_gmt":"2022-11-08T04:00:41","guid":{"rendered":"http:\/\/www.glc.us.es\/~jalonso\/exercitium\/?p=7503"},"modified":"2022-12-14T11:49:07","modified_gmt":"2022-12-14T09:49:07","slug":"suma-de-los-digitos-de-una-cadena","status":"publish","type":"post","link":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/suma-de-los-digitos-de-una-cadena\/","title":{"rendered":"Suma de los d\u00edgitos de una cadena"},"content":{"rendered":"<p>Definir la funci\u00f3n<\/p>\n<pre lang=\"text\">\n   sumaDigitos :: String -> Int\n<\/pre>\n<p>tal que <code>sumaDigitos xs' es la suma de los d\u00edgitos de la cadena<\/code>xs`. Por ejemplo,<\/p>\n<pre lang=\"text\">\n   sumaDigitos \"SE 2431 X\"  ==  10\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 Data.Char (digitToInt, isDigit)\nimport Test.QuickCheck\n\n-- 1\u00aa soluci\u00f3n\n-- ===========\n\nsumaDigitos1 :: String -> Int\nsumaDigitos1 xs = sum [digitToInt x | x <- xs, isDigit x]\n\n-- 2\u00aa soluci\u00f3n\n-- ===========\n\nsumaDigitos2 :: String -> Int\nsumaDigitos2 [] = 0\nsumaDigitos2 (x:xs)\n  | isDigit x  = digitToInt x + sumaDigitos2 xs\n  | otherwise  = sumaDigitos2 xs\n\n-- 3\u00aa soluci\u00f3n\n-- ===========\n\nsumaDigitos3 :: String -> Int\nsumaDigitos3 xs = sum (map digitToInt (filter isDigit xs))\n\n-- 4\u00aa soluci\u00f3n\n-- ===========\n\nsumaDigitos4 :: String -> Int\nsumaDigitos4 = sum . map digitToInt . filter isDigit\n\n-- Comprobaci\u00f3n de equivalencia\n-- ============================\n\n-- La propiedad es\nprop_sumaDigitos :: String -> Bool\nprop_sumaDigitos xs =\n  all (== sumaDigitos1 xs)\n      [sumaDigitos2 xs,\n       sumaDigitos3 xs,\n       sumaDigitos4 xs]\n\n-- La comprobaci\u00f3n es\n--    \u03bb> quickCheck prop_sumaDigitos\n--    +++ OK, passed 100 tests.\n\n-- Comparaci\u00f3n de eficiencia\n-- =========================\n\n-- La comparaci\u00f3n es\n--    \u03bb> sumaDigitos1 (take (4*10^6) (cycle \"ab12\"))\n--    3000000\n--    (1.92 secs, 819,045,328 bytes)\n--    \u03bb> sumaDigitos2 (take (4*10^6) (cycle \"ab12\"))\n--    3000000\n--    (1.79 secs, 856,419,112 bytes)\n--    \u03bb> sumaDigitos3 (take (4*10^6) (cycle \"ab12\"))\n--    3000000\n--    (0.62 secs, 723,045,296 bytes)\n--    \u03bb> sumaDigitos4 (take (4*10^6) (cycle \"ab12\"))\n--    3000000\n--    (0.63 secs, 723,045,552 bytes)\n<\/pre>\n<p><a name=\"python\"><\/a><br \/>\n<b>Soluciones en Python<\/b><\/p>\n<pre lang=\"python\">\nfrom sys import setrecursionlimit\nfrom timeit import Timer, default_timer\n\nfrom hypothesis import given\nfrom hypothesis import strategies as st\n\nsetrecursionlimit(10**6)\n\n# 1\u00aa soluci\u00f3n\n# ===========\n\ndef sumaDigitos1(xs: str) -> int:\n    return sum((int(x) for x in xs if x.isdigit()))\n\n# 2\u00aa soluci\u00f3n\n# ===========\n\ndef sumaDigitos2(xs: str) -> int:\n    if xs:\n        if xs[0].isdigit():\n            return int(xs[0]) + sumaDigitos2(xs[1:])\n        return sumaDigitos2(xs[1:])\n    return 0\n\n# 3\u00aa soluci\u00f3n\n# ===========\n\ndef sumaDigitos3(xs: str) -> int:\n    r = 0\n    for x in xs:\n        if x.isdigit():\n            r = r + int(x)\n    return r\n\n# Comprobaci\u00f3n de equivalencia\n# ============================\n\n# La propiedad es\n@given(st.text())\ndef test_sumaDigitos(xs: str) -> None:\n    r = sumaDigitos1(xs)\n    assert sumaDigitos2(xs) == r\n    assert sumaDigitos3(xs) == r\n\n# La comprobaci\u00f3n es\n#    src> poetry run pytest -q suma_de_digitos_de_cadena.py\n#    1 passed in 0.41s\n\n# Comparaci\u00f3n de eficiencia\n# =========================\n\ndef tiempo(e: str) -> None:\n    \"\"\"Tiempo (en segundos) de evaluar la expresi\u00f3n e.\"\"\"\n    t = Timer(e, \"\", default_timer, globals()).timeit(1)\n    print(f\"{t:0.2f} segundos\")\n\n# La comparaci\u00f3n es\n#    >>> tiempo('mayorExponente1(2, 2**(2*10**4))')\n\n\n# Comparaci\u00f3n de eficiencia\n# =========================\n#\n# La comparaci\u00f3n es\n#    >>> tiempo('sumaDigitos1(\"ab12\"*5000)')\n#    0.00 segundos\n#    >>> tiempo('sumaDigitos2(\"ab12\"*5000)')\n#    0.02 segundos\n#    >>> tiempo('sumaDigitos3(\"ab12\"*5000)')\n#    0.00 segundos\n#\n#    >>> tiempo('sumaDigitos1(\"ab12\"*(5*10**6))')\n#    1.60 segundos\n#    >>> tiempo('sumaDigitos3(\"ab12\"*(5*10**6))')\n#    1.83 segundos\n<\/pre>\n","protected":false},"excerpt":{"rendered":"<p>Definir la funci\u00f3n sumaDigitos :: String -> Int tal que sumaDigitos xs&#8217; es la suma de los d\u00edgitos de la cadenaxs`. Por ejemplo, sumaDigitos \u00abSE 2431 X\u00bb == 10 Soluciones A continuaci\u00f3n se muestran las soluciones en Haskell y las soluciones en Python. Soluciones en Haskell import Data.Char (digitToInt, isDigit) import Test.QuickCheck &#8212; 1\u00aa soluci\u00f3n&#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":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/7503"}],"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=7503"}],"version-history":[{"count":3,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/7503\/revisions"}],"predecessor-version":[{"id":7653,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/7503\/revisions\/7653"}],"wp:attachment":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/media?parent=7503"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/categories?post=7503"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/tags?post=7503"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}