Unbounded Knapsack Problem with Memoization

Knapsack.java

public class Knapsack {
  
    public static void main(String[] args) {

        int val[] = new int[]{0, 60, 100, 120};
        int wt[] = new int[]{0, 10, 20, 30};
        int W = 50;
        int n = val.length-1;
        int[][] memo = new int[n+1][W+1];

        for (int i = 0; i < memo.length; i++) {
            for (int j = 0; j < memo[i].length; j++) {
                memo[i][j] = -1;
            }
        }

        System.out.println(Knapsack.knapsack(wt, val, W, n, memo));
    }

    public static int knapsack(int[] weights, int[] values, int capacity, int index, int[][] memo) {

        if (memo[index][capacity] != -1) return memo[index][capacity];

        //base case
        if (index <= 0 || capacity <= 0) return 0;

        int result = 0;

        if (weights[index] > capacity) {
            result = knapsack(weights, values, capacity, index-1, memo);
        } else {
            int temp1 = knapsack(weights, values, capacity, index-1, memo);
            int temp2 = values[index] + knapsack(weights, values, capacity-weights[index], index-1, memo);
            result = Math.max(temp1, temp2);
        }
        memo[index][capacity] = result;
        return result;

    }
}