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@endolith
Last active June 22, 2022 23:33
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GCD and LCM functions in Python for several numbers
# Greatest common divisor of 1 or more numbers.
from functools import reduce
def gcd(*numbers):
"""
Return the greatest common divisor of 1 or more integers
Examples
--------
>>> gcd(5)
5
>>> gcd(30, 40)
10
>>> gcd(120, 40, 60)
20
"""
# Am I terrible for doing it this way?
from math import gcd
return reduce(gcd, numbers)
# Least common multiple is not in standard libraries? It's in gmpy, but this
# is simple enough:
def lcm(*numbers):
"""
Return lowest common multiple of 1 or more integers.
Examples
--------
>>> lcm(5)
5
>>> lcm(30, 40)
120
>>> lcm(120, 40, 60)
120
"""
def lcm(a, b):
return (a * b) // gcd(a, b)
return reduce(lcm, numbers, 1)
# Assuming numbers are positive integers...
@TheFern2
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TheFern2 commented Nov 1, 2017

For python3 use
from math import gcd
fraction gcd has been deprecated.

@tyler-austin
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what does *numbers look like? What is the expected parameter?

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ghost commented Jan 7, 2018

Thanks for it!!

@AaronConlon
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thank you!

@Tardis07
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Excellent! How elegant it is.

@goutham9032
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For case of n no's in python 2.7

>>> from fractions import gcd
>>> def get_gcd(*nos):
...     return reduce(gcd,nos)
... 
>>> get_gcd(120,40,60)
20
>>> get_gcd(30,40)
10

@Ericwonne
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thanks very much for the sharing

@kkimdev
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kkimdev commented Aug 19, 2018

Concatenated everything for the convenience.

from functools import reduce
from fractions import gcd

def lcm(a, b):
    return a * b / gcd(a, b)

def lcms(*numbers):
     return reduce(lcm, numbers)

def gcds(*numbers):
     return reduce(gcd, numbers)

@kovalevcon
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kovalevcon commented Jan 14, 2019

Last update for Python 3:

from functools import reduce
from math import gcd

def lcm(a, b):
    return int(a * b / gcd(a, b))

def lcms(*numbers):
    return reduce(lcm, numbers)

@endolith
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Author

@kovalevcon Why int(float division) instead of int division?

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ghost commented Mar 25, 2019

Easy! Just do:
import math
ans = math.gcd(8, 10)
For lcm, do:
import math
ans = math.lcm(8, 10)
or:
import math
gcd_ans = math.gcd(8, 10)
lcm_ans = 8 * 10 / gcd_ans
I got it from this site:
https://www.geeksforgeeks.org/gcd-in-python/
Check it out!

@vloddos
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vloddos commented May 19, 2019

I think there should be floordiv instead of truediv in your lcm

@SmilingBytes
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SmilingBytes commented Jul 21, 2019

import math

def lcm(a, b):
    return int(a * b / math.gcd(a, b))
print(lcm(2, 6))

@yegane-AI
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Great code! Can you plz explain me how does GCD works in your program?

@SohaibAnwaar
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Use this line of code to take LCM. Its fast and give you LCM of multiple numbers

import numpy as np
divisor_list = [3,4,5,6,7,2]
int(np.lcm.reduce(divisor_list))

@yegane-AI
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Use this line of code to take LCM. Its fast and give you LCM of multiple numbers

import numpy as np
divisor_list = [3,4,5,6,7,2]
int(np.lcm.reduce(divisor_list))

Thanks alot

@astrojuanlu
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It's not mentioned here, but this is the Euclidean algorithm for computing the GCD: https://en.wikipedia.org/wiki/Euclidean_algorithm

Love how short the code is!

@naemazam
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def find_gcd(a,b):
gcd = 1
for i in range(1,a+1):
if a%i==0 and b%i==0:
gcd = i
return gcd

first = int(input('Enter first number: '))
second = int(input('Enter second number: '))

print('HCD of %d and %d is %d' %(first, second, find_gcd(first, second)))

lcm = first * second / find_gcd(first, second)
print('MCM of %d and %d is %d' %(first, second, lcm))
print("azam")

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