Use of 'temp' in pseudocode

Question

I tried researching here, and on the internet in general, but since pseudocode writing is rather diverse and many use different signs for different things, I couldn't find anything that might fit my question.

Given the following: an array A (not necessarily already sorted) of the order n, and the indexes p,r so that 1<=p<=r<=n;

I am given the following recursive algorithm (in pseudocode), and I wonder what specific two lines (bolded) in it do/mean:

MAXB(A,p,r)

if p=r

then return A[p]

else temp<-----MAXB(A,p,r-1)

if temp>=A[r]

then return temp

else return A[r]

I do not exactly understand the process that is done with the 'temp'. If it changes MAXB(A,p,r) into MAXB(A,p,r-1) how can it be compared to the value of A[r] at all? I know the algorithm certainly doesn't do what it is supposed to do, according to the description: return the index of the item with the highest value, between A[p] and A[r] - certainly doesn't do that, yet I am not sure how can the temp even be compared to any value.

Answer 1

It looks to me like temp is a variable.

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It's making a recursive call to your funciton: MAXB and storing the value from that call in a variable called temp.

It's then checking whether or not temp is greater than or equal to A[r], and if it is, than it returns temp. If it is less than A[r] it returns A[r]

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Here's an explanation of the entire function:

if p=r
    then return A[p]

if p and r are equal, than there is only one value between A[p] and A[r], and therefore, that one values is the greatest and you return that value.

else 
    temp<-----MAXB(A,p,r-1)

You use your own function, MAXB to get the greatest value between A[p] and A[r-1], and you store that in temp

if temp>=A[r]
    then return temp
else 
    return A[r]

you compare to greatest value between A[p] and A[r-1] to A[r]. Whichever one is greater, must be the greatest value between A[p] and A[r], and is therefore the value that you want to return.