http://harvardsportsanalysis.files.wordpress.com/2011/06/shortest_possible_baseball_road_trip1.pdf ]]>

To minimize the trip duration (in days) required to visit every ballpark, set the cost on each arc as its duration in days, and find a unit circulation flow such that the flow out and into the external node is one with a side constraint that the sum of the flow out of game nodes at each distinct stadium is exactly one (so that you leave each stadium once). This is a network flow problem with flow bundle constraints, but should be relatively easy to solve to optimality with off-the-shelf integer programming software. You could also attempt to instead minimize driving distance.

I might actually make this into a homework problem…

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