Dynamic_Stack_Implementation

package ds.Dynamic_Stack;

public class Runner {

public static void main(String[] args)
{
  Stack stack = new Stack();
  stack.size();
  stack.push(10);
  stack.size();
  stack.push(10);
  stack.size();
  stack.push(10);
  stack.size();
  stack.push(10);
  stack.size();
  stack.push(10);
  stack.size();
  stack.size();
  stack.push(10);
  stack.size();
  stack.push(10);
  stack.size();
  stack.pop();
  stack.size();
  stack.pop();
  stack.pop();
  stack.size();
  stack.pop();
  stack.size();
  stack.pop();
  stack.pop();
  stack.pop();
  stack.pop();
  stack.pop();
  stack.pop();
  stack.pop();
  stack.size();

}

}

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package ds.Dynamic_Stack;

public class Stack 

{

int[] stack = new int[2];

int  top = 0;

int capacity = 2;

public void push(int data) 

{

if(top == capacity)

expand();

stack[top] = data;

top++;

}

private void expand() 

{

System.out.println("Expanding");

int[] newStack = new int[capacity*2];

System.arraycopy(stack, 0, newStack, 0, stack.length);

stack = newStack;

capacity = capacity *2;

}

public void show() 

{

for(int n :stack)

System.out.print(n+" ");

}

public void pop() 

{

int data;

if(top<=0)

{

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

return;

}

else

{

top--;

data  = stack[top];

stack[top]= 0;

shrink();

}

System.out.println("Popped Data: "+data);

}

private void shrink() 

{

System.out.println("Shrinked");

  int size = stack.length;

  if(size<capacity/2)

  {

  int s1 = capacity/2;

  int[] ShrinkedArray = new int[s1];

  System.arraycopy(stack, 0, ShrinkedArray, 0, stack.length);

  stack = ShrinkedArray;

  }

}

public int  peek() 

{

if(top<=0)

{

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

return 0;

}

else

{

int data;

data  = stack[top -1];

return data;

}

}

public void size() 

{

  //return (top);

  System.out.println("Size: "+top);

}

public void  isEmpty() 

{

  if(top<=0)

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

  

  else

  System.out.println("Stack is NOT Empty");

  

}

}

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