Question about listing all possible combination given n and k (Python)

Question

Good day. I was searching for how to list all possible combinations of numbers 1 to n taken k numbers. I cam across some algorithms and recursive methods. But I am fairly new to coding so I have a hard time understanding complex codes. Can someone tell me a way I can think of this problem so that I can put it into code? I am not allowed to use intertools so I may have to do an iterative or recursive version.

all_combination(3 , 2)

should return

[[1,2],[1,3],[2,3]]

The problem is called "Combinations N choose K". It is not trivial. One reference (not simple): stackoverflow.com/questions/127704/… — NoChance
– NoChance, Commented Oct 31, 2020 at 13:27

Hamza · Accepted Answer · 2020-10-31 13:21:30Z

1

You can use:

from itertools import combinations 
list(combinations(range(1,n+1), k))

putting n=3, k=2 produces:

[(1, 2), (1, 3), (2, 3)]

answered Oct 31, 2020 at 13:21

Hamza

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3 Comments

Tony Suffolk 66 Over a year ago

Standard library for the win :-)

superb rain Over a year ago

@TonySuffolk66 Yeah, fortunately only "intertools" is forbidden.

Tony Suffolk 66 Over a year ago

Why - it is part of the standard language ? Banning it's use seems perverse to me.

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