/**

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

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

if (nums == null || nums.length < 3) return res;

Arrays.sort(nums);

if (nums[0] > 0 || nums[nums.length-1] < 0) return res;

for (int i=0; i<nums.length-2; i++) {

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

int l = i+1;

int r = nums.length-1;

int left = 0 - nums[i];

while (l < r) {

if (nums[l] + nums[r] == left) {

res.add(Arrays.asList(nums[i], nums[l], nums[r]));

while (l < r && nums[l] == nums[l+1]) l++;

while (l < r && nums[r] == nums[r-1]) r--;

l++;

r--;

} else if (nums[l] + nums[r] > left) {

r--;

} else {

l++;

}

}

}

return res;

}

public static void main(String[] args) {

ThreeSum15 ts = new ThreeSum15();

System.out.println(ts.threeSum(new int[]{-1, 0, 1, 2, -1, -4}));

System.out.println(ts.threeSum(new int[]{0, 0, 0}));

System.out.println(ts.threeSum(new int[]{0, 0, 0, 0}));

System.out.println(ts.threeSum(new int[]{-4, -2, -2, -2, 0, 1, 2, 2, 2, 3, 3, 4, 4, 6, 6}));

System.out.println(ts.threeSum(new int[]{0, 0, 0, 1, 1}));

System.out.println(ts.threeSum(new int[]{-1, -1, 0, 0, 0}));

}