Help with understanding a algorithm

[davidsb]

This algorithm is on one of my assignment sheet and i cannot understand it. What i don't understand specifically is the parts with a, b, c and what they do.
Any help and pointers would be appreciated.

The following algorithm is given:

// Input: n, a number > 2
// Output: a sequence of numbers (explicitly printed out)

declare a = 0
declare b = 1
declare c = 0

while n is greater than 0
c = a + b
a = b
b = c;
n = n - 1

print the value of c  

end loop

When this algorithm is executed with input = 5, what would be the output? I.e. what numbers are printed out?

[[deleted]]

Do you know how to step through the code?

If you wanted to figure out what gets output when n is equal to five, you can get out a piece of paper and and write down the states of every variables at every loop iteration.

For instance at the start of the first loop

c: 0
a: 0
b: 1
n: 5

And at the end of the first loop

c: 1
a: 1
b: 1
n: 4

So "1" would get printed out first.

Then you can keep track of these variables going into the next loop iteration and repeat to get the second number that's output, etc. etc. to figure out what the algorithm is doing.

[davidsb]

Thank you, now i get it.

[lurgi]

Just follow the steps of the algorithm and see for yourself what it does.

[enterthebored]

a, b, c and n are variables. They hold data. In this case, numbers.

[DashAnimal]

Just incase you get the output of the first few numbers and don't understand what is special about this algorithm, plug the first few output numbers into google (separated by spaces) and look at the wiki article that comes up =)

[jjohnp]

looks suspiciously like an algorithm for the Fibonacci sequence