Let s be a stack. Consider the following program:

s. push (1);

s. push (2);

s. push (3);

s. pop ();

s. push (4);

s. pop ();

s. pop ();

int x = s. peek ();

What is the value of x after the assignment statement?

Hi

In the first scenario we have

S = []

then:

S=[1],

S=[2,1]

S=[3,2,1]

S=[2,1]

S=[4,2,1]

S=[2,1]

S=[1]

So when it's call the method peek to S, X will be assigned 1

Explanation:

Stack is a linear data structure which follows a particular order in which the operations are performed. The order may be LIFO (Last In First Out). There are many real-life examples of a stack. Consider an example of plates stacked over one another in the canteen. (Taken from wikipedia)

- The method push is to put the element on the top of the stack

- The method pop is take out the top element of the stack

- The method peek is to see what is the top element of the stack