Iterative Cartesian Product in Java

Question

I want to compute the cartesian product of an arbitrary number of nonempty sets in Java.

I\'ve wrote that iterative code...

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Answer 1

The following answer uses iteration and not recursion. It uses the same Tuple class from my previous answer.

It is a separate answer because IMHO both are valid, different approaches.

Here is the new main class:

public class Example {

    public static  List> cartesianProduct(List> sets) {
        List> tuples = new ArrayList>();

        for (Set set : sets) {            
            if (tuples.isEmpty()) {
                for (T t : set) {
                    Tuple tuple = new Tuple();
                    tuple.add(t);    
                    tuples.add(tuple);
                }                
            } else {
                List> newTuples = new ArrayList>();

                for (Tuple subTuple : tuples) {
                    for (T t : set) {
                        Tuple tuple = new Tuple();
                        tuple.addAll(subTuple);
                        tuple.add(t);
                        newTuples.add(tuple);
                    }
                }                

                tuples = newTuples;
            }
        }

        return tuples;
    }
}