Function to find triplet sum zero

problem id:-http://practice.geeksforgeeks.org/problems/find-triplets-with-zero-sum/1

code:-

bool findTriplets(int a[], int n)
{ 
for(int i=0;i<n-1;++i)
    {
    unordered_set<int> s;
    for(int j=i+1;j<n;++j)
        {
        int num=-(a[i]+a[j]);
        if(s.find(num)!=s.end())
            return true;
        else
            s.insert(a[j]);
        }
    }
return false;
}