public List<List<Integer>> fourSum(int[] nums, int target) {

Arrays.sort(nums);

//HashSet<List<Integer>> hs = new HashSet<List<Integer>>();

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

for (int i = 0; i < nums.length - 3; i++) {

for (int j = i + 1; j < nums.length - 2; j++) {

int small = j + 1;

int large = nums.length - 1;

while (small < large) {

int sum = nums[i] + nums[j] + nums[small] + nums[large];

if (sum > target) large--;

else if (sum < target) small++;

else {

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

solution.add(nums[i]);

solution.add(nums[j]);

solution.add(nums[small++]);

solution.add(nums[large--]);

//if (!hs.contains(solution)) {

if (!result.contains(solution)) {

//hs.add(solution);

result.add(solution);

}

}

}

}

}

return result;

}

}