Line Number 139,
fast is pointing to head->next why ?
in explanation slow and fast pointing at first element of the LL.
can u explain ?
At time stamp 6:19
@premang its becoz imagine both cases
1st n odd
1 2 3 is linklist slow =1 and fast=2 therefore fast comes on null and slow on 2 so it works
2nd n even
1 2 3 4 slow=1 fast=2 fast comes on 4 and slow on 2 so now mid = 2
so basically if you are considering mid as 2 in even u start from fast = head next while if u consider 3 as mid then both as head.
i hope your doubt is resolved if yes dont forget to mark the doubt as resolved 
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