public List<List<Integer>> threeSum(int[] nums) {

Arrays.sort(nums);

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

final int n = nums.length;

for (int i = 0; i < n - 2; i++) {

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

int start = i + 1;

int end = n - 1;

final int target = -nums[i];

while (start < end) {

if (nums[start] + nums[end] < target) {

start++;

} else if (nums[start] + nums[end] > target) {

end--;

} else {

res.add(Arrays.asList(nums[i], nums[start], nums[end]));

while (start < end && nums[start + 1] == nums[start]) { start++; }

while (start < end && nums[end - 1] == nums[end]) { end--; }

start++;

end--;

}

}

}

return res;

}