title: adjacency list for graph build
body: <p>Can someone please tell me what kind of adjacency list i have to make to build a graph with appropriate nodes and links? I have to make a tree structure to define ajdacency list? Or is there another way?<br>
  Not interested in matrix now, thank you.</p>
  
  <p>can i for example make an arraylist with other arralists inside every position to the other nodes of the edges to have like:</p>
  
  <pre><code>nodes {a,b,c}, connection {{a-c},{b,c}}
  </code></pre>
  
  <p>so i have and arraylist or my adjacency list <code>[a[c],b[c],c[a,b]]</code></p>