{"id":7451,"date":"2022-10-20T06:00:31","date_gmt":"2022-10-20T04:00:31","guid":{"rendered":"http:\/\/www.glc.us.es\/~jalonso\/exercitium\/?p=7451"},"modified":"2022-12-14T12:28:48","modified_gmt":"2022-12-14T10:28:48","slug":"suma-elementos-consecutivos","status":"publish","type":"post","link":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/suma-elementos-consecutivos\/","title":{"rendered":"Suma de elementos consecutivos"},"content":{"rendered":"<p>Definir la funci\u00f3n<\/p>\n<pre lang=\"text\">\n   sumaConsecutivos :: [Integer] -> [Integer]\n<\/pre>\n<p>tal que <code>sumaConsecutivos xs<\/code> es la suma de los pares de elementos consecutivos de la lista xs. Por ejemplo,<\/p>\n<pre lang=\"text\">\n   sumaConsecutivos [3,1,5,2]  ==  [4,6,7]\n   sumaConsecutivos [3]        ==  []\n   last (sumaConsecutivos [1..10^8])  ==  199999999\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 Test.QuickCheck\n\n-- 1\u00aa soluci\u00f3n\n-- ===========\n\nsumaConsecutivos1 :: [Integer] -> [Integer]\nsumaConsecutivos1 xs = [x+y | (x,y) <- zip xs (tail xs)]\n\n-- 2\u00aa soluci\u00f3n\n-- ===========\n\nsumaConsecutivos2 :: [Integer] -> [Integer]\nsumaConsecutivos2 xs = zipWith (+) xs (tail xs)\n\n-- 3\u00aa soluci\u00f3n\n-- ===========\n\nsumaConsecutivos3 :: [Integer] -> [Integer]\nsumaConsecutivos3 = zipWith (+) <*> tail\n\n-- 4\u00aa soluci\u00f3n\n-- ===========\n\nsumaConsecutivos4 :: [Integer] -> [Integer]\nsumaConsecutivos4 (x:y:zs) = x+y : sumaConsecutivos4 (y:zs)\nsumaConsecutivos4 _        = []\n\n-- Comprobaci\u00f3n de equivalencia\n-- ============================\n\n-- La propiedad es\nprop_sumaConsecutivos :: [Integer] -> Bool\nprop_sumaConsecutivos xs =\n  all (== sumaConsecutivos1 xs)\n      [sumaConsecutivos2 xs,\n       sumaConsecutivos3 xs,\n       sumaConsecutivos4 xs]\n\n-- La comprobaci\u00f3n es\n--    \u03bb> quickCheck prop_sumaConsecutivos\n--    +++ OK, passed 100 tests.\n\n-- Comparaci\u00f3n de eficiencia\n-- =========================\n\n-- La comparaci\u00f3n es\n--    \u03bb> last (sumaConsecutivos1 [1..8*10^6])\n--    15999999\n--    (1.98 secs, 2,176,566,784 bytes)\n--    \u03bb> last (sumaConsecutivos2 [1..8*10^6])\n--    15999999\n--    (0.19 secs, 1,408,566,840 bytes)\n--    \u03bb> last (sumaConsecutivos3 [1..8*10^6])\n--    15999999\n--    (0.19 secs, 1,408,566,936 bytes)\n--    \u03bb> last (sumaConsecutivos4 [1..8*10^6])\n--    15999999\n--    (2.78 secs, 2,560,566,832 bytes)\n<\/pre>\n<p>El c\u00f3digo se encuentra en <a href=\"https:\/\/github.com\/jaalonso\/Exercitium\/blob\/main\/src\/Suma_elementos_consecutivos.hs\">GitHub<\/a>.<\/p>\n<p><a name=\"python\"><\/a><br \/>\n<b>Soluciones en Python<\/b><\/p>\n<pre lang=\"python\">\nfrom operator import add\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 sumaConsecutivos1(xs: list[int]) -> list[int]:\n    return [x + y for (x, y) in zip(xs, xs[1:])]\n\n# 2\u00aa soluci\u00f3n\n# ===========\n\ndef sumaConsecutivos2(xs: list[int]) -> list[int]:\n    return list(map(add, xs, xs[1:]))\n\n# 3\u00aa soluci\u00f3n\n# ===========\n\ndef sumaConsecutivos3(xs: list[int]) -> list[int]:\n    if len(xs) >= 2:\n        return [xs[0] + xs[1]] + sumaConsecutivos3(xs[1:])\n    return []\n\n# Comprobaci\u00f3n de equivalencia\n# ============================\n\n# La propiedad es\n@given(st.lists(st.integers(min_value=1, max_value=100)))\ndef test_sumaConsecutivos(xs: list[int]) -> None:\n    r = sumaConsecutivos1(xs)\n    assert sumaConsecutivos2(xs) == r\n    assert sumaConsecutivos3(xs) == r\n\n# La comprobaci\u00f3n es\n#    src> poetry run pytest -q suma_elementos_consecutivos.py\n#    1 passed in 0.26s\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('sumaConsecutivos1(range(1, 10**4))')\n#    0.00 segundos\n#    >>> tiempo('sumaConsecutivos2(range(1, 10**4))')\n#    0.00 segundos\n#    >>> tiempo('sumaConsecutivos3(range(1, 10**4))')\n#    0.18 segundos\n#\n#    >>> tiempo('sumaConsecutivos1(range(1, 10**8))')\n#    8.34 segundos\n#    >>> tiempo('sumaConsecutivos2(range(1, 10**8))')\n#    6.28 segundos\n<\/pre>\n<p>El c\u00f3digo se encuentra en <a href=\"https:\/\/github.com\/jaalonso\/Exercitium-Python\/blob\/main\/src\/suma_elementos_consecutivos.py\">GitHub<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Definir la funci\u00f3n sumaConsecutivos :: [Integer] -> [Integer] tal que sumaConsecutivos xs es la suma de los pares de elementos consecutivos de la lista xs. Por ejemplo, sumaConsecutivos [3,1,5,2] == [4,6,7] sumaConsecutivos [3] == [] last (sumaConsecutivos [1..10^8]) == 199999999 Soluciones A continuaci\u00f3n se muestran las soluciones en Haskell y las soluciones en Python. Soluciones&#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\/7451"}],"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=7451"}],"version-history":[{"count":4,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/7451\/revisions"}],"predecessor-version":[{"id":7666,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/posts\/7451\/revisions\/7666"}],"wp:attachment":[{"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/media?parent=7451"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/categories?post=7451"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.glc.us.es\/~jalonso\/exercitium\/wp-json\/wp\/v2\/tags?post=7451"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}