With a single 6-faced dice, calculate the possible ways to reach a certain number

Question

I have the following Java assignment. In a board game I can roll a 6-faced dice and move forward the same number of spaces. If the goal is “n” spaces away from the starting point, how do I implement a program that calculates all possible ways there are to arrive exactly at the "n"? I'm squeezing my head but I can't find the solution, I have searched the net but nothing is what I want exactly. I know it's not that hard, I just can't find the correct way to do it.

Thanks in advance.

Answer 1

There are multiple ways to do this, so I'm going to keep it generic. Determine all possible permutations, storing the values. Generate a roll, getting the total. Sift through the permutations that match the total.

class Roll {
    int first;
    int second;
    int total;

    public Roll(int first, int second) {
        this.first = first;
        this.second = second;
        this.total = first + second;
     }

 List<Roll> permutations = new ArrayList<>();
 for (int ii = 1; ii < 7; ii++)
     for (int jj = 1; jj < 7; jj++)
         permutations.add(new Roll(ii,jj);

 roll the dice, determine the total;
 now loop through the permutations to find the 
   total matching the roll total. These are your combinations. 
   This solution doesn't handle duplicate rolls. For example 1,6 and 6,1;