What is the complexity of finding the predecessor of a node in a doubly linked list? This is a question from Cormen 3rd edition(exercise 10.1). I am of the opinion that the complexity should be O(1), as we just have to look into the next pointer of the current node. 

But the answers from the web suggest that it should be O(n). Where am I getting it wrong?

Can someone please help me out???

Thanks in advance!
Both answers look wrong. Time is indeed $O(1)$ because you can look into prev (not next) pointer of the node. The answers you found on the web are probably about single-linked lists.