CODEWITHSUNDEEP
algorithmmathfactorial
Hi There
Hi There

Reputation: 15

factorial algorithm in pseudo code

I've been given the following algorithm, that takes a positive integer K and returns a value:

X = 1
Y = 1
while X ≠ K do
    X = X + 1
    Y = Y * x
return Y

I'm supposed to figure out what it returns.

As it happens, I know the answer — it returns the factorial of K — but I don't understand why.

How do you go about figuring out what this pseudocode does?

Upvotes: 0

Views: 10634

Answers (3)

Fallen
Fallen

Reputation: 4565

this piece of code can be simply rewritten as (in C/C++/Java),

for(X=1;X<=K;X++){
    Y=Y*X;
}

Now it describes it self :-)

Upvotes: 0

G.Srinivas Kishan
G.Srinivas Kishan

Reputation: 438

Now let's assume that K is 5. Therefore the factorial of 5 is 120. Then as you enter the loop X value is 2 and y gets the value 2.(1*2) Then the value of X is 3 after getting into loop, which then makes the value of Y 6 because (3*2). Then the value of X is 4 after getting into loop, which then makes the value of Y 24 because (4*6). Then the value of X is 5 after getting into loop, which then makes the value of Y 120. Then since X==Y the while loop exits and Y value which is the factorial is returned.

Upvotes: 0

rnbguy
rnbguy

Reputation: 1399

X = 1 <- this is counter which you gonna multiply in every step
Y = 1 <- this is to store the cumulative product after each step
while X ≠ K do <- until you reach K
    X = X + 1 <- increase X
    Y = Y * X <- multiply with increased X
return Y <- return the product

So in the loop the cumulative product goes like this 1 -> 1*2 - > 2*3 -> 6*4 -> ... -> 1*2*..*(K-1)*K which is K!

Upvotes: 1

Related Questions