specific Knapsack Algorithm [duplicate]

This question is an exact duplicate of:

How can I solve it? KnapSack - values all the same but each other object has three weights 1 answer

I have problem with solve the specific knapsack algorithm problem. Is there someone who give me some tips or help me? I solved it by Brute Force method but the execute time is very long (I checked all possible combinations and take the best solution - it works). I need to solve it by Dynamic Programming or Greedy Algorithm (but better by DP). I read about it a lot and I can't find the solution with it ;/ It is hard exercise. HERE IS description of my exercise

HERE ARE TESTS FOR THIS EXERCISE

There are a few good tutorials on the internet that explain the Knapsack problem thoroughly.

More specifically, I would recommend this specific one, where the problem and the DP-approach is entirely explained, including the solution in three different languages (including Java).

// A Dynamic Programming based solution for 0-1 Knapsack problem
class Knapsack
{
    // A utility function that returns maximum of two integers
    static int max(int a, int b) { return (a > b)? a : b; }

   // Returns the maximum value that can be put in a knapsack of capacity W
    static int knapSack(int W, int wt[], int val[], int n)
    {
         int i, w;
     int K[][] = new int[n+1][W+1];

     // Build table K[][] in bottom up manner
     for (i = 0; i <= n; i++)
     {
         for (w = 0; w <= W; w++)
         {
             if (i==0 || w==0)
                  K[i][w] = 0;
             else if (wt[i-1] <= w)
                   K[i][w] = max(val[i-1] + K[i-1][w-wt[i-1]],  K[i-1][w]);
             else
                   K[i][w] = K[i-1][w];
         }
      }

      return K[n][W];
    }

    // Driver program to test above function
    public static void main(String args[])
    {
        int val[] = new int[]{60, 100, 120};
        int wt[] = new int[]{10, 20, 30};
        int  W = 50;
        int n = val.length;
        System.out.println(knapSack(W, wt, val, n));
    }
}
/*This code is contributed by Rajat Mishra */

Source: GeeksForGeeks