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

Arrays.sort(nums);

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

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

if (i > 0 && nums[i] == nums[i - 1]) {

continue;

}

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

if (j != i + 1 && nums[j] == nums[j - 1]) {

continue;

}

long newTarget = target - nums[i] - nums[j];

for (int k = j + 1, m = nums.length - 1; k < m; ) {

long sum = nums[k] + nums[m];

if (sum > newTarget) {

m--;

} else if (sum < newTarget) {

k++;

} else {

result.add(Arrays.asList(nums[i], nums[j], nums[k], nums[m]));

for (k++, m--; k < m && nums[k] == nums[k - 1] && nums[m] == nums[m + 1]; k++, m--);

}

}

}

}

return result;

}