Question

Introduced to data structure using java

2)One of the applications of stack is to convert infix expressions to postfix. Given the following infix expression, use the stack method to convert it to postfix. Show your work.

x - y / (a + b) + z

3)write a generic method to find the maximum of three variables of generic type (i.e. type T).

Note that you must use the compareTo method to compare the values. Also, the code must return one of the values. Therefore the return type must be T.

Answer 1

import java.util.*;
public class DataStructuresEg
 {
    
    //Method to convert infix expression to postfix
      public static void infixToPostfix(String infix)
  {
    //Stack stk to store values
    Stack<Character> stk=new Stack<Character>();
    //String to store postfix expression
      String postfix="";
      //initializing variable i
      int i=0;
     //Loop to access each character in input expression 
    while(i<infix.length())
    {
        //if the input character is a letter or a digit
        if(Character.isLetter(infix.charAt(i))||Character.isDigit(infix.charAt(i)))
        {
          //add the input character to string postfix
            postfix+=" "+infix.charAt(i);
        }
        //else if the input character is an ')'
        else if(infix.charAt(i)=='(')
        {
          //push the input character into stack
            stk.push('(');

        }
        //else if the input character is ')'
        else if(infix.charAt(i)==')')
        {
            //Repeat  while stack is not empty and stack of top is "("
            while(stk.peek()!='(' && !stk.isEmpty())
            {
              //Delete the top element in stack and add to postfix
             postfix+=" "+stk.pop();
            }
            //if top element in stack is'('
            if(stk.peek()=='(')
            //Delete the top element in stack 
           stk.pop();
        }
        //else if the input character is blankspace do nothing
        else if(infix.charAt(i)==' ')
          {}
          //Else if the element is an operator
        else
        {
           //Repeat  while stack is not empty and 
           //precedence of stack of top is greaater thanor equalto precedence of input 
            while( !stk.isEmpty()&&(prec(infix.charAt(i))<=prec(stk.peek())))
             //Delete the top element in stack and add to postfix
                  postfix+=" "+stk.pop();
              //push the input character to stack
             stk.push(infix.charAt(i));
        
           
        }
       //increase i
        i++;
    }
    //Repeat  while stack is not empty 
    while(!stk.isEmpty())
    //Pop elements in stack and add to postfix
      postfix+=" "+stk.pop();
    System.out.println("Postfix Expression is");
    //Print the postfix expression
    System.out.println(postfix);
  } 
  //Function to find precedence of operator
  static int prec(char op)
  {
      int p=0;
      switch(op)
      {
        //if input is ^ precedence value is 3
         case '^':p=3;
          break;
          //if input is * or / or % precedence value is 2
          case '*':p=2;
          break;
          case '/':
          case '%': p=2;
                break;
                //if input is + or - precedence value is 1
        case '+':p=1;
        break;

        case '-':
                    p=1;
                    break;
      }
      return p;
  }
  //Generic function tofind maximum of three 
public static <T extends Comparable> void maxOfThree(T a,T b,T c)
{
  //Declaring generic variable max tostore mximum value
  T max;
  //if a is greater than b and c
  if(a.compareTo(b)>=0 && a.compareTo(b)>=0)
    max=a;
    //if b is greater than a and c
  else if(b.compareTo(c)>=0)
    max=b;
  else
    max=c;
  System.out.println("Maximum of three is: "+max);

}
  public static void main(String[] args) 
{
  //calling function to find maximum of three inputs of different types 
  maxOfThree(3,36, 8);
  maxOfThree(39.7,36.9, 0.8);
  maxOfThree('a','d','z');
 System.out.println("Enter infix expreession:");
 Scanner sc=new Scanner(System.in);

String input=sc.nextLine();
//calling function to find postfix expression
 infixToPostfix(input);

}
 }

Sample output