class Solution {

public List<List<Integer>> combinationSum(int[] candidates, int target) {

List<List<Integer>> res = new ArrayList<>();

subsets(0, candidates, new ArrayList(), res, target);

return res;

}

void subsets(int index, int[] nums, List<Integer> temp, List<List<Integer>> res, int target){

if(target==0){

res.add(new ArrayList(temp));

}

if(target<0){

return;

}

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

temp.add(nums[i]);

subsets(i, nums, temp, res, target-nums[i]);

temp.remove(temp.size()-1);

}

}

}