如何编写返回数组中所有可能解决方案的回溯方法？

Question

I am student and I am stuck on this problem:

The method gets an Array of Items and a certain amount of "money" as an Integer. Every Item has a "prize" and a description. Now I have to find all possible combinations of Items that could be bought with the money. The supply of each Item is infinite and they can be bought several times.

I've managed to come up with a basic Algorithm that returns me the FIRST possible solution, but I have no idea how to get to the point where it returns ALL possible Solutions.

I'm thankful for any input!

Answer 1

An array of found solutions has a problem: an array is fixed-length in java. Use a List instead, and pass that as parameter, to be filled.

Instead of a single solution:

Solution s = search(param);

do:

List<Solution> solutions = new ArrayList<>();
search(param, solutions);
for (Solution s : solutions) {
    System.out.println(s);
}

with

void search (Param param, List<Solution> solutions) {
    ...
    if (solved) {
        solutions.add(new Solution(...));
        return;
    }
}