Question

STACK Data Structure using JAVA

1. In a FILO structure, elements are processed in reverse order, in which they arrive. Suppose during execution, an element of the stack becomes least important in terms of priority and has to be but at the bottom of the stack.

Method Signature: public void decreasePriority(<AnyType> el)

Write an operator that places a certain element of the stack at the bottom of the stack.

Answer 1

public java.util.Stack;

public class StackProgram<AnyType>
{
   private Stack<AnyType> stack;
  
   public StackProgram()
   {
       stack = new Stack<AnyType>();
   }
  
   // method that places a certain element of the stack at the bottom of the stack
   public void decreasePriority(AnyType el)
   {
       Stack<AnyType> tempStack = new Stack<AnyType>(); // create a new stack
       // push all elements of stack to tempStack except element el
       while(!stack.isEmpty()
       {
           if(!stack.peek().equal(el))
               tempStack.push(stack.pop());
       }  
      
       stack.push(el); //push el at the bottom of the stack
       // push the rest of the elements to stack
       while(!tempStack.isEmpty())
           stack.push(tempStack.pop());
   }
}