static class Solution {

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

if(nums.length < 3) return Collections.EMPTY_LIST;

Arrays.sort(nums);

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

int last = nums[0];

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

if(i != 0 && last == nums[i]) continue;

if(nums[i] > 0) break;

int left = i+1;

int right = nums.length -1;

while (left < right) {

if (nums[i] + nums[left] + nums[right] == 0) {

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

list.add(nums[i]);

list.add(nums[left ++]);

list.add(nums[right --]);

res.add(list);

while (left < right && nums[left] == nums[left -1]) {left++;} // avoid duplicates

while (left < right && nums[right] == nums[right + 1]) {right--;} // avoid duplicates

}

if (nums[i] + nums[left] + nums[right] > 0) {

right --;

}

if (nums[i] + nums[left] + nums[right] < 0) {

left ++;

}

}

last = nums[i];

}

return res;

}

}

public static void main(String[] args) {

new Solution().threeSum(new int[]{-1,0,1,2,-1,-4});

}