1. 2 sum
2. 3 sum
3. Pythagorean triple
Find a Pythagorean triplet from an array. c^2 = a^2 + b^2.
void pt(int arr[], int size)
{
for(int i=0; i<size; i++)
arr[i] *= arr[i];
for(int k=size-1; k>=2; k--)
{
for(int l=0, r=k-1; l<r;)
{
if(arr[k] == arr[l] + arr[r])
{
cout<<arr[k]<<" = "<<arr[l++]<<" + "<<arr[r--]<<endl;
}
else if(arr[k] > arr[l] + arr[r])
l++;
else if(arr[k] < arr[l] + arr[r])
r--;
}
}
}