title: How to find path of exact length in graph
body: <p>I would like to find path of fixed length (given while running the program) in undirected graph. I'm using adjacency matrix of my graph.<br>
  I tried to use some algorithms like DFS or A*, but they only return the shortest path.  </p>
  
  <p>Nodes can't be visited again.  </p>
  
  <p>So let's say that my graph have 9 nodes and the shortest path is built from 4 nodes.<br>
  I want to have additional variable that will "tell" the algorithm that I want to find path which have 7 nodes (for example) and it will return nodes which are included in my expected path {1,2,4,5,6,7,8}.<br>
  Of course, if there is no solution for path that I want, it will return nothing (or it will return path close to my expactations, let's say 19 instead of 20).</p>
  
  <p>Someone told be about DFS with backtracking, but I don't know anything about it.<br>
  Could someone explain how to use DFS with backtracking or recommend some other algorithms to solve that problem?</p>