package StackDataStructure;

public class StackImplementation {

private int len = 10;

private int arr[] = new int[len];

private int top = -1;

void push(int d) {

if(top == len-1) {

len = 2*len;

int brr[] = new int[len];

for(int i=0;i<=top;i++) {

brr[i] = arr[i];

}

top++;

arr = brr;

arr[top] = d;

return;

}

top++;

arr[top] = d;

}

int peek() {

if(top == -1) {

System.out.println("Stack is Empty");

return -1;

}

return arr[top];

}

int pop() {

if(top == -1) {

System.out.println("Underflow");

return -1;

}

else {

int val = arr[top];

top--;

return val;

}

}

void display() {

for(int i=top;i>=0;i--) {

System.out.print(arr[i]+" ");

}

System.out.println();

}

public static void main(String[] args) {

StackImplementation s = new StackImplementation();

s.push(10);

s.push(20);

s.push(30);

s.push(40);

s.push(50);

s.push(60);

s.display();

System.out.println("Peek "+ s.peek());

System.out.println("Pop "+s.pop());

s.display();

s.push(60);

s.push(70);

s.push(80);

s.push(90);

s.push(100);

s.push(110);

s.display();

}

}