Min #Stack operations

Question

Let's consider we have a stack with three operations defined on it:: Push,Pop, Peek

We have to print "ABCACBA" using the above operations.

Give the min no of operations for doing it and also specify the operations in order.

Comments

I got 11 operations.

push A

peek = A

push B

peek = B

push C

peek = C

push A

pop A = A

pop = C

pop  = B

pop = A

stack is empty.

---

Is it peek or "print"? I am getting 16 of these 3 operations which prints exact string !

---

Peek is used to simply print topmost element of a stack.

Simply I am using logic

first push ABC ____ pop CBA

but to fill that blank space where A is there I'm pushing and popping that extra A.

Is my ans correct?

---

yes, correct.

---

@Aswin after you pushed A you are simply popping it not printing it you should print it and then pop it same goes for next operations @ Tuhin what is the given answer is it 11?

---

@saxena0612

Peek and pop both gives output.

Only difference is peek doesn't take out top element out of the stack but pop does.

---

thanks got it now !

---

@ashwin kulakarni

Why are u making stack as empty in the end?

Answer 1

push A→ peek A→push B→peek B→push c→peek C→push A→peek A→pop A→pop C→peek C→pop B→peek B→peek A    14 operations     (assuming if it doesn’t matter is stack is empty) and if matters that stack should be empty then 15 operations)