How can I find all path of a graph(no loop) with a fix end node?

Question

I want to find all path start with node a and end with node b.

Now my solution is that start from a to exec DFS and select path ends with b.

The complexity is O(egde + node), can it be optimized to O(path + node)?

Thanks!

Answer 1

DFS has O(n), it means linear complexity, it cannot be improved in non-sorted graphs.