Question

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?

Answer 1

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

Step-by-step 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