CareerCup

Given 3 unsorted arrays A, B and C you need to find all possible combinations such that A[i] + B[j] = B[k] + C[l].

Given the arraylist<meals> input, find the number of dishes with unique ingredients.

class meals{
        String cuisine;
        ArrayList<String> dish = new ArrayList<String>();
        meals(String s, String[] arr){
                cuisine = s;
                for(String i:arr){
                    dish.add(i);
                }
        }
    }

Example:
Input: [
{
"cuisine" : "American",
"dish" : ["lettuce", "cheese", "olives", "tomato"]
},
{
"cuisine" : "Mexican",
"dish" : ["lettuce", "cheese", "pepper", "tomato"]
},
{
"cuisine" : "French",
"dish" : ["lettuce", "cheese", "pepper", "tomato"]
},
{
"cuisine" : "Continental",
"dish" : ["lettuce", "cheese", "olives", "tomato"]
},
]

Output: 2

Because there are two unique ingredient-dishes; {Mexican, French} and {American, Continental}.

I have tried different methods, but could not get to the solution. Thank you!