Question

Suppose that you are asked to modify the Stack class to add a new operation max() that returns the current maximum of the stack comparable objects. Assume that pop and push operations are currently implemented using array a as follows, where item is a String and n is the size of the stack. Note: if x andy are objects of the same type, use x.compareTo(y) to compare the objects x and y public void push String item ) { [n++] = iten; } public String pop { return al--n]; } Implement the max operation in two ways, by writing a new method using array a (in 8.1), or updating push and pop methods to track max as the stack is changed (in 8.2). Q8.1 Implement method maxi 5 Points Write a method max() using Out) space and Oin) running time. public String max() {...} Enter your answer here Q8.2 Update push() and popo 5 Points Write a method max() using On) space and 011) run time. You may update the push and pop methods as needed public void push {...} public String pop() {...} public String max() {...}

Answer 1

Answer:

Following are the code to the given points:

Explanation:

For point 8.1:

public String max()//defining a method max

{

   String maxVal=null;//defining a string variable that holds a value

   for(int x=0;x<n;x++)

   {

       if(maxVal==null || a[i].compareTo(maxVal)>0)//defining if blok to comare the value

       {

           maxVal=a[i];//holding value in maxVal variable

       }

   }

   return maxVal;//return maxVal variable value

}

For point 8.2:

public void push(String item)//defining a method push that accepts item value in a parameter

{

       a[n]=item;//defining an array to hold item value

       if(n==0 || item.compareTo(maxVals[n-1])>0)//use if to comare item value

       {

               maxVals[n]=item;//holding item value in maxVals variable

       }

       else

       {

               maxVals[n]=maxVals[n-1];//decreasing the maxVals value

       }

       n++;//incrementing n value

}

public String pop()//defining a method pop

{

       return a[--n];//use return value

}

public String max()//defining a method max

{

       return maxVals[n-1];//return max value

}

• In the first point, the max method is declared that compares the string and returns its max value.
• In the second point, the push, pop, and max method are declared that works with their respective names like insert, remove and find max and after that, they return its value.