# My O(n^2) solution

• This is my code of solution. No hash was used. Only for and while loop.

``````public List<List<Integer>> threeSum(int[] num) {
List<List<Integer>> list = new ArrayList<List<Integer>>();
List<Integer> n = new ArrayList<Integer>();
int count = 0;

if(num.length<3) return list;

// Sort the array in an non-decreasing order
quickSort(num, 0, num.length-1);

for(int i=1; i<num.length; i++) {
int left = i-1;
int right = i+1;
while(left >= 0 && right <= num.length-1) {
if(num[right]+num[left]+num[i] == 0) {
List<Integer> triplet = new ArrayList<Integer>();
right++;
left--;
} else if (num[left]+num[right]+num[i]>0) {
left--;
} else {
right++;
}
}
}

for(int i=0; i<list.size(); i++) {
for(int j=i+1; j<list.size(); j++) {
if(list.get(i).get(0)==list.get(j).get(0)
&&list.get(i).get(1)==list.get(j).get(1)
&&list.get(i).get(2)==list.get(j).get(2))
{
list.remove(j);
j--;
}
}
}

return list;
}``````

Looks like your connection to LeetCode Discuss was lost, please wait while we try to reconnect.