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Comment by IanCal | Hacker News Reader

You need to swap the 1 at the end for an 11.

Also, this code for me returns 2672 solutions although I don't believe all are valid due to integer division. Perhaps a python 2 -> python 3 difference? (py2 here)

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I have the same number, do you think there is a reason why they are not all valid? EDIT: actually the number I calculate is 2796. Also using Python 2..

Partly it might be due to needing "-10" at the end rather than -1 (I think I may have corrected it to -11 by mistake).

However, larger is the difference in how division works.

Python2: 3 / 2 => 1

Python3: 3 / 2 => 1.5

Would forcing the integer result fix this problem? Something like:

    def f(a, b, c, d, e, f, g, h, i):
        return a + int((13 * b * i + g * h * c) / (i * c)) + d + 12 * e - f - 11 - 10

If I try it like this, I still have the same number of solutions... Maybe I'm missing something..

EDIT: code formatting...

No, the problem is the other way around. Keeping them as integers and just using '/' is what's causnig the problem. You can either force them to be floats (not the result, the parameters in the calculation), or you can explicitly look for divisions that have remainders.

At the end should be 10.

And with checks to have only divisions without the remainder I get 20 solutions, the first one being (3, 2, 1, 5, 4, 7, 8, 9, 6)?

Yes, I get the same.

Edit - Ah yes, 10, sorry.

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