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javaadditionunary-function

Using unary representation with addition java string

I need to write a code that takes a string input and turns it, or something to that effect, into a valid unary equation with addition to verify if it is valid. I'm confused, could anyone point me in the direction of understanding this? An example would be: 111+1111=11111+1+1 is the statement 3+4=5+1+1 which is valid. My other question would be how to use stacks to do unary operations.

Solution

  • If you are limited to this language then your can write a simple parser using a number of methods. You can first split your String

    String[] parts = eqn.split("=");

    Then split each part:

    String[] left = parts[0].split("\\+");
String[] right = parts[1].split("\\+");

    Now you can simply count the lengths of the strings:

    int leftside = 0;
for (String l : left) {
    leftside += l.length;
}

    and so on for the right side and see if they are equal.

    There are many other ways you can tackle this.

    Basically you have to write a parser. You might want to use a character-by-character scanner, or use regexes or a generic tool such as ANTLR. It depends on your final goal and whether it is likely to change. Are you likely to have characters other than 1, +, =, for example?

    My guess is this is homework. And I guess that you are expected to read character-by-character and push() each character on a stack. Then you have to pop() the stack when you encounter certain conditions.I'm not going to do this for you...