title: graph path on hadoop with python
body: <p>Hy guys, i have to write an algorithm in python with the map reduce paradigm that has to run on hadoop:</p>
  
  <p>Let us assume that given a directed graph G = (V,E), an edge (v,u) ∈ E means that v is
  following u, or that v has declared u being his friend, therefore u has the potential to influence v (but not necessarily the other way around). Now, given a network G = (V,E) and a node v ∈ V , we want to find all the nodes u such that there exists a path from v to u of length at most 3. Design and implement an algorithm for Hadoop that finds all such nodes. Assume that the input file(s)
  give the adjacency list for each node, that is, they are of the form v:u1 ,u2 ,u3 . . .
  where v is a node and each ui corresponds to the edge (v,ui ).</p>
  
  <p>I have not idea how to implement map and reduce tasks.</p>