```import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Deque;
import java.util.List;
import java.util.Stack;

public class Solution {

public List<List<Integer>> threeSum(int[] nums) {
List<List<Integer>> res = new ArrayList<>();
int len = nums.length;

// 特判 1
if (len < 3) {
return res;
}

// 排序是去重复的前提
Arrays.sort(nums);
// [0, 1, 2, 3] 4
for (int i = 0; i < len - 2; i++) {
// 特判 2
if (nums[i] > 0) {
break;
}

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

int left = i + 1;
int right = len - 1;
// 注意：这里是严格小于
while (left < right) {
int sum = nums[i] + nums[left] + nums[right];

if (sum == 0) {
List<Integer> cur = new ArrayList<>();

// 剪枝 2
while (left < right && nums[left + 1] == nums[left]) {
left++;
}
while (left < right && nums[right - 1] == nums[right]) {
right--;
}

left++;
right--;

} else if (sum > 0) {
// 后面的数太大了，让它往前走一步试试看
right--;
} else {
// sum < 0， 前面的数太小了，让它往后走一步试试看
left++;
}
}
}
return res;
}

public static void main(String[] args) {
int[] nums = {0, 0, 0, 0};
Solution solution3 = new Solution();
List<List<Integer>> res = solution3.threeSum(nums);
res.forEach(System.out::println);

List<Integer> res1 = new ArrayList<>();

Deque<Integer> stack = new ArrayDeque<Integer>();
}
}
```