import java.util.*;
public class Solution {
public ArrayList<ArrayList<Integer>> threeSum(int[] num) {
Arrays.sort(num);
ArrayList<ArrayList<Integer>> list = new ArrayList<>();
for(int i = 0; i < num.length - 2; i++){
if(i > 0 && num[i] == num[i-1]) continue;
int target = -num[i];
int l = i+1,r = num.length - 1;
while(l < r){
if(num[l] + num[r] == target){
list.add(new ArrayList<Integer>(Arrays.asList(-target,num[l],num[r])));
l++; r--;
while(l < r && num[l] == num[l-1]) l++;
while(l < r && num[r] == num[r+1]) r--;
}else if(num[l] + num[r] < target){
l++;
}else {
r--;
}
}
}
return list;
}
}