1 class Solution { 2     public int combinationSum4(int[] nums, int target) { 3         int[] res = new int[target + 1]; 4         res[0] = 1; 5         for(int i = 1; i <= target; i++) { 6             for(int j = 0; j < nums.length; j++) { 7                 if(nums[j] <= i && res[i - nums[j]] > 0) { 8                     res[i] += res[i - nums[j]] ; 9                 }10             }11         }12         return res[target];13 14         15     }16 }