Problem 1172. Wheat on a chessboard pt 1

Created by Robert Turner

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If a chessboard were to have wheat placed upon each square such that one grain were placed on the first square and each successive square after had double the amount of grains as the square before. How many grains of wheat would be on the chessboard at the finish?

Assume the chess board is n by n squares.

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Last Solution submitted on Mar 30, 2020

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Ken Campbell on 5 Jan 2013

Shouldn't the solution for n=-1 be NaN, rather than 'NaN' which is a character array?

Aurelien Queffurust on 7 Jan 2013

I agree with Ken , we expect NaN and not the string 'NaN'

James on 7 Jan 2013

I believe you should also change the assert for the case n=-1 to be isequalwithnan, since isequal(NaN,NaN) is false.

Aurelien Queffurust on 8 Jan 2013

yeap you have just rescored the problem but you need to use isequalwithnan,

Prateep Mukherjee on 8 Jan 2013

actually you need to use isequalwithequalnans

Jan Orwat on 11 Apr 2014

tests 5 and 6 does not work properly. those numbers are out of precision, and for test 6 it couldn't be fixed even with uint64 used instead of type double

Massimo Zanetti on 19 Oct 2016

This problem is simply wrong. The right answer is

sum(1:2^(n^2-1))

if we where to sum ALL the grains on the board....

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Grzegorz Knor on 10 Sep 2014

Sorry for cheating, I didn't notice that there is string 'NaN' in test suite.

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Problem 1172. Wheat on a chessboard pt 1

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Problem 1172. Wheat on a chessboard pt 1

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