title: Using A* to solve Travelling Salesman
body: <p>I've been tasked to write an implementation of the A* algorithm (heuristics provided) that will solve the travelling salesman problem. I understand the algorithm, it's simple enough, but I just can't see the code that implements it. I mean, I get it. Priority queue for the nodes, sorted by distance + heuristic(node), add the closest node on to the path. The question is, like, what happens if the closest node can't be reached from the previous closest node? How does one actually take a "graph" as a function argument? I just can't see how the algorithm actually functions, as code.</p>
  
  <p>I read the Wikipedia page before posting the question. Repeatedly. It doesn't really answer the question- searching the graph is way, way different to solving the TSP. For example, you could construct a graph where the shortest node at any given time always results in a backtrack, since two paths of the same length aren't equal, whereas if you're  just trying to go from A to B then two paths of the same length are equal.</p>
  
  <p>You could derive a graph by which some nodes are never reached by always going closest first.</p>
  
  <p>I don't really see how A* applies to the TSP. I mean, finding a route from A to B, sure, I get that. But the TSP? I don't see the connection.</p>