Question

Hello, I need help with following question

- Write a method to implement below question. You can use either StackArrayBased or StackListBased to create the stack.

L= {ww':w is a string of characters w' = reverse (w)}

Note: The empty string, a string with less than 2 characters, or a string with an odd number of characters will not be in the languege.

Answer 1

Please find attached the java program which has stack implementation array based
Copy the below java function in file named Reverse.java
Run it as 'javac Reverse.java' and then java Reverse. Or you can copy paste the code in eclipse.

/* Reverse.java*/

import java.util.*;

class ArrayStack {
   private int maxsize;
   private char[] stackarray;
   private int top;
  
   public ArrayStack(int size) {
       maxsize = size;
       stackarray = new char[maxsize];
       top = -1;
   }
  
   public void push(char x) {
       this.top++;
       stackarray[top] = x;
   }
  
   public char pop() {
       return stackarray[top--];
   }
  
   public boolean isEmpty() {
       if (this.top == -1)
           return true;
       return false;
   }
  
   public boolean isFull() {
       if (this.top == maxsize -1)
           return true;
       return false;
   }
}
public class Reverse {

   public static void main(String[] args) {
       System.out.println("Enter the string");
      
       Scanner s = new Scanner(System.in);
       String input = s.next();
      
       if(input.length() < 2 || input.length() %2 != 0){
           System.out.println(input + " is not in L");
           System.exit(1);
       }
       ArrayStack stack = new ArrayStack(input.length() / 2);
      
       for(int i = 0; i < (input.length() / 2); i++) {
           char c = input.charAt(i);
           stack.push(c);
       }
      
       for(int i = input.length()/2; i<input.length(); i++) {
           char c = stack.pop();
           if (c != input.charAt(i)) {
               System.out.println(input + " is not in L");
               System.exit(1);
           }
                      
       }
      
       System.out.println(input + " is in L");

   }

}