Comment on I wish

affiliate@lemmy.world ⁨10⁩ ⁨months⁩ ago

def is_even(n: int):
    if n ==0：
        return True
    elif n < 0:
        return is_even(-n)
    else:
        return not is_even(n-1)

• affiliate@lemmy.world ⁨10⁩ ⁨months⁩ ago

  here’s a constant time solution:

  def is_even(n: int):
      import math
      return sum(math.floor(abs(math.cos(math.pi/2 * n/i))) for i in range(1, 2 ** 63)) > 0
  

  spoiler

  i can’t imagine how long it’ll take to run, my computer took over 3 minutes to compute one value when the upper bound was replaced with 2^30^. but hey, at least it’s O(1).

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  • Acters@lemmy.world ⁨10⁩ ⁨months⁩ ago

    Nice, how about bitwise & operator?

    // n&1 is 1, then odd, else even
    
    return (!(n & 1));
    

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• Karyoplasma@discuss.tchncs.de ⁨10⁩ ⁨months⁩ ago

  Don’t use recursion. Each call will need to allocate a new stack frame which leads to being slower than an iterative approach in pretty much any language.

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  • recapitated@lemmy.world ⁨10⁩ ⁨months⁩ ago

    TCO baby

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    • 257m@sh.itjust.works ⁨10⁩ ⁨months⁩ ago

      Since when did Python have tail call optimization?

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