Stack

Question

If two stack is growing  two opposite end of array. Then which logic works and how?

Comments

Can you please explain the question?

Answer 1

As much i understand from  question two stack implementation using single array.

Array[1........n]

Stack1 with top1=0 [when element added in stack1 top1++] push increment and pop decrement in top1.

stack2 with top2=n+1[when element added in stack2 top2--]push decrement and pop increment in top2(may be bug as A[n+1] so we set top2 acc]

if array full top1 +1 =top2

if array empty top1=n-top2+1

Comments

I havenot got

plz elaborate more

any link?

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A[1......10] here top1=0 top2=-1

>at starting 1.stack top1=0

 push 5 top1++ i.e 1

push 7 top1++ i.e 1+1=2

push 1 the top1 become3

2.stack2 top2 =-1(assume)

(First push(3)

 top2=n=10  as top2==-1

then

next pushes(2) top2-- i.e 9 ]

First push in stack2 i.e when top2=-1 then top2 will be set to n,further push will just decrement top2.

for more see push and pop code.

https://www.geeksforgeeks.org/implement-two-stacks-in-an-array/

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https://gateoverflow.in/1000/gate2004-3 question is well framed. & It's mentioned that space is used efficiently & stack grows from topmost then top2=top1+1