Little puzzle on functional programming in Python

Question

The input is two integers in one line, x and y. I need to write a basically one-line program which does different things with x and y, and prints the result. Say, the output should be x + 1, y * y. Or list(range(x)), y // 2. Whatever operations but different. No def functions, also 'if' and 'for' are prohibited. As far as i understand, should look something like:

print(
    *map(
        lambda x: ??? ,
        map(
            int, input().split()
        )
    )
)

(But lambda can only do same thing to both inputs, right? ) I know it is possible and i've been thinking about this for three days to no avail. Most probable i miss something very obvious.

Right? Wrong. You can pass as many parameters to lambda as you like. — DYZ
– DYZ, Commented Sep 14, 2018 at 23:49
Input many parameters - yes. Output a tuple - yes. The problem is that output = fixed function of input. Normally one would simply write: x, y = map(int(input().split()) print(x+1) print(y*y) But it has to be done without intermediate x,y and in one line — Alex Bachurin
– Alex Bachurin, Commented Sep 14, 2018 at 23:59

Patrick Haugh · Accepted Answer · 2018-09-14 23:55:34Z

1

Your lambda function can take an x and y and turn them into pretty much any expression. Then you would call that function, doing the processing of the inputs outside of that lambda

print(*(lambda x, y: (x+1, y*y))(*map(int, input().split())))
print(*(lambda x, y: (list(range(x)), y//2))(*map(int, input().split())))

answered Sep 14, 2018 at 23:55

Patrick Haugh

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1 Comment

Alex Bachurin Over a year ago

Thank you! I had a mental block indeed :) Very simple

melpomene · Accepted Answer · 2018-09-14 23:56:37Z

0

This seems to work just fine:

print(
    *(lambda x: [int(x[0]) + 1, int(x[1]) * int(x[1])])(
        input().split()
    )
)

No fancy functional tricks or map are needed.

answered Sep 14, 2018 at 23:56

melpomene

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1 Comment

Alex Bachurin Over a year ago

Thank you! I had a mental block indeed :) Several previous tasks in my course were heavy on map, filter etc.

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