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ltwagnon's avatar
ltwagnon
Ret. Employee
Feb 24, 2017

Security Challenge #2 Answers

Our DevCentral Security Challenge 2 is found here: https://devcentral.f5.com/articles/security-month-on-devcentral-challenge-2   This is the Q&A placeholder for answers to be posted. Once you ha...
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security
Stanislas_Piro2's avatar
Stanislas_Piro2
Icon for Cumulonimbus rankCumulonimbus
Feb 28, 2017
sum (1 -> x) = (x*(x+1))/2
sum even (if x is even) (1 -> x) = (x/2*(x/2 +1)
sum odd (1-> x) = (x*(x+1))/2 - (x/2*(x/2 +1))
 = x/2 * ((x+1) - (x/2 +1))
 = x/2 * (x - x/2)

the tcl code is :

 

% set x 4976
4976
 to convert odd to next even number if number is odd
%set x [expr {($x-1)/2*2+2}]
4976
%set result [expr {$x/2 * ($x - $x/2) }]
6190144