public class Solution {

    /**

     * @param nums: an integer array and all positive numbers

     * @param target: An integer

     * @return: An integer

     */

     public int backPackV(int[] nums, int target) {

        // Write your code here

        int[] f = new int[target + 1];

        f[0] = 1;

        for (int i = 0; i < nums.length; ++i)

            for (int  j = target; j >= nums[i]; --j)

                f[j] += f[j - nums[i]];

        return f[target];

    }

}