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Asked: 2024-09-27T00:04:43+05:30 In:

How can you efficiently calculate the LCM of two numbers in Python under 50 bytes?

I came across this interesting problem that involves calculating the least common multiple (LCM) in Python, and it got me thinking about how compact we can make our code while solving it. The challenge revolves around creating an efficient function that can compute the LCM of two numbers—ideally in 50 bytes or less!

Let’s be real: LCM isn’t always at the forefront of programming tasks, but it’s such a neat concept. It’s all about finding that smallest number that two integers can both divide into without leaving any remainder. For instance, if you have the numbers 4 and 5, the LCM is 20 since that’s the smallest number divisible by both of them. Simple enough, right?

So here’s the kicker: how do you manage to write this LCM function in just 50 bytes of Python? I’ve seen some attempts that cleverly use built-in functions or clever tricks with arithmetic, but I really want to see what creative solutions people can come up with!

One thing that has me curious is how you handle edge cases, like when one of the numbers is zero or negative. Do you throw an exception, return a specific value, or handle it in some other slick way? Also, are there any inherent limitations in the Python language that you think might complicate the task in such a concise format?

Your solutions would also be fun to compare! I’m interested in seeing different approaches and implementations. Maybe someone will use a mix of lambda functions, recursion, or even some innovative use of Python libraries to keep the byte count low.

And hey, for the extra challenge: can you explain your reasoning or logic behind your solution? I think it would add a layer of understanding for those of us who are less versed in this compact coding style.

Looking forward to seeing everyone’s creative takes on this LCM conundrum!

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    2 Answers

    1. lcm = lambda a, b: a * b // gcd(a, b) if a and b else 0

      This code defines a compact function for calculating the least common multiple (LCM) of two numbers, using Python’s built-in function gcd to first find the greatest common divisor.

      If either of the numbers is zero, the function simply returns 0, since LCM is not defined in those cases. This way, we gracefully handle edge cases without throwing exceptions.

      This solution is concise and keeps the byte count under 50 bytes while still being effective. Hope you find this helpful!

    2. To calculate the Least Common Multiple (LCM) of two numbers in Python efficiently, we can utilize the relationship between the greatest common divisor (GCD) and LCM. The LCM can be computed as the product of the two numbers divided by their GCD. Below is a compact implementation that fits within the 50-byte limit, using the built-in `math.gcd` function for simplicity: 

          
      from math import gcd as g;lcm=lambda a,b:a*b//g(a,b)

      This function, `lcm`, takes two parameters, `a` and `b`, and applies the formula mentioned above to find the LCM efficiently. Edge cases, such as when either number is zero, can be addressed by adding a simple conditional check, returning zero according to the mathematical definition (since the LCM is undefined when one of the numbers is zero). The concise nature of this implementation demonstrates Python’s ability to handle operations compactly, while still leveraging existing libraries to reduce the byte count further.

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