title: how to input this for Dijkstra algorithm question
body: <p>I have an assignment on Dijkstra's algorithm, but the question has me confused about the input. It asks me to find shortest and second shortest paths, and that part I have figured out, but how do I even start with the graph has me troubled. 
  The question says the input has to be read from a file and the file contains the number of nodes and the weight between two nodes. Weight between two nodes should be 1 to 9, and can use 0 to indicate a path that doesn't exist.
  Now my question is what has to be the contents of the file? I was able to understand Dijkstra's algorithm where the input was a 2d array that represents the graph. Can someone clarify what is expected from this question? Like what the source file should contain. </p>