Question

Hi I have a problem in my code, I have to count the variables used in an expression and when two or more variables are same it should be counted as 1. For example, a+ab = the total number of variable used: 2. The problem is when I inputted a+a =total number of variable used: 2.
Here’s my code:

public void simplify(String strexp){
    int ex =strexp.length();

    for (int a=0;a<=ex-1;a++){
        if(a==0)
        {
        if (Character.isLetter(strexp.charAt(a)))
        {
        b++;
       }


        }
        else{
        for(int c=0;c<=a-1;c++){
              if (Character.isLetter(strexp.charAt(c))==Character.isLetter(strexp.charAt(a)))
              {

                System.out.println("equal");
                break;
              }
              else if (Character.isLetter(strexp.charAt(c))!=Character.isLetter(strexp.charAt(a)))
              {
             //if(c==a-1)
              //{
               b++;
               System.out.println("nomatch");
           //  }
               }
        }
        }
        }
   JOptionPane.showMessageDialog(null, b);
    }

Answer 1

Use a list to count the total amount of variables

public static int simplify(String strexp) {
    int length = strexp.length();

    List<Character> usedVariables = new ArrayList<Character>();
    for (int i = 0; i < length; i++) {
        char c = strexp.charAt(i);
        if (Character.isLetter(c) && !usedVariables.contains(c)) {
            usedVariables.add(c);
        }
    }

    return usedVariables.size();
}

public static void main(String[] args) {
    System.out.println(simplify("x + b = d"));
    System.out.println(simplify("x + x = a"));
    System.out.println(simplify("x + x = x / 2"));
}

This prints out

3
2
1