title: Strategy to find your best route via Public Transportation only?
body: <p>Finding routes for a car is pretty easy: you store a weighted graph of all the roads and you could use <a href="http://en.wikipedia.org/wiki/Djikstra%27s_algorithm" rel="noreferrer">Djikstra's algorithm</a> [1]. A bus route is less obvious. With a bus you have to represent things like "wait 10 minutes for the next bus" or "walk one block to another bus stop" and feed those into your pathfinding algorithm.</p>
  
  <p>It's not even always simple for cars. In some cities, some roads are one-way-only into the city in the morning, and one-way-only out of the city in the evening. Some advanced GPSs know how to avoid busy routes during rush hour.</p>
  
  <p>How would you efficiently represent this kind of time-dependent graph and find a route? There is no need for a provably optimal solution; if the traveler wanted to be on time, they would buy a car. ;-)</p>
  
  <p>[1] A wonderful algorithm to mention in an example because everyone's heard of it, though A* is a likelier choice for this application.</p>