I think it only takes 5 weighings when N=128. Am I incorrect?
agree 5 weighing for N=128 (worst case scenario you reduce to 43 15 5 2 1 after each consecutive weighing)
the last test case provided by the author is wrong: should be 5 since log(128)/log(3) < 5.
The problem is that the author do not specify an strategy. And as mentioned, dividing by 3 yields a better strategy than 6 weightings for 128. But, my guess is that the author counted the number of divisions instead of the number of weightings 128->[42 42 43] -> [14 14 14; 14 14 15]->[5 5 4; 5 5 5]->[2 2 0; 2 2 1]->[1;2]->1.
Correct the test suite
Similar Triangles - find the height of the tree
Replace all zeros and NaNs in a matrix with the string 'error'
Replace multiples of 5 with NaN
How many digits are there?
Side of an equilateral triangle
Reverse the elements of an array
RMS value from a set of observations
Find out missing number from a vector of 9 elements
Generate pi using logarithm
Find the solution of algebraic equation
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