Multiple Stacks in Single Array

Question

Consider the implementation of multiple stacks in single array S of size P from index 0 to P – 1. Number of stack Q each of size P/Q. 

Now, how push() and pop() implemented in it. Can somebody give some insight on this implementation

Comments

I think we know the start and end of each stack right then we can push and pop normally as we do for a single stack but here multiple we have to use multiple top's

Am I wrong?

---

Consider stack numbered as 0,1,2....(P/Q-1).

Size of each stack is fixed( P/Q).  So, allocation of the stacks will be like--

Stack 0-- Index 0 to Index (P/Q-1)

Stack 1-- Index P to Index (2*P/Q-1)

....

....

Stack (P/Q-1) --- Index( (P/Q-1)*P) to Index (P/Q*P/Q-1)

 

For a stack 'n'( n starting form 0 and ending at (P/Q-1)) the condition for top empty and full stack will change. Top  being as top0, top1, top2... topN. Initially before any push or pop the values of top being

top0 = 0*P/Q-1,

top1= 1*P/Q-1

...

topN = (P/Q-1)*P/Q-1

Stack operations will be something just like this.

IsEmpty(Stack-n){

if( topN == (n*P/Q) -1 )

return Stack-n is empty

}

IsFull(Stack-n){

if( topN == (((n+1)*P/Q)-1 )

}

Answer 1

Consider stack numbered as $0,1,2....(P/Q-1)$.

Size of each stack is fixed$( P/Q)$.  So, allocation of the stacks will be like--

Stack 0-- Index 0 to Index $(P/Q-1)$

Stack 1-- Index P to Index $(2*P/Q-1)$

....

....

Stack (P/Q-1) --- Index$( (P/Q-1)*P)$ to Index $(P/Q*P/Q-1)$

 

For a stack 'n'( n starting form 0 and ending at $(P/Q-1))$ the condition for top empty and full stack will change. Top  being as $top0, top1, top2... topN$. Initially before any push or pop the values of top being

$top0 = 0*P/Q-1$,

$top1= 1*P/Q-1$

...

$topN = (P/Q-1)*P/Q-1$

Stack operations will be something just like this.

$IsEmpty(Stack-n)${

$if( topN == (n*P/Q) -1 )$
        return Stack-n is Empty

}

$IsFull(Stack-n)${

$if( topN == (((n+1)*P/Q)-1 )$

     return Stack-n is Full

}