Problem Detail: For a given input $N$, how many times does the enclosed statement executes?
for $i$ in $1ldots N$ loop
$quad$for $j$ in $1ldots i$ loop
$quad$$quad$for $k$ in $ildots j$ loop
$quad$$quad$$quad$$sum = sum + i$ ;
$quad$$quad$end loop;
$quad$end loop;
end loop;
Can anyone figure out an easy way or a formula to do this in general. Please explain.
Asked By : Vishnu Vivek
Answered By : Bartosz Przybylski
You need to solve simple formula $sum_{i=1}^Nsum_{j=1}^isum_{k=i}^j1$ this will give you overall result of $frac{1}{6}N(N+1)(N+2)$ Math is easy to do here but I used Wolfram Alpha
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Question Source : http://cs.stackexchange.com/questions/7008
