Lazy salesman - Rik van Grol - IPP 29

Rik created this souvenir puzzle for the IPP 29 held in San Francisco in 2009.

Your goal is to wind the thread to all the locations on the map and ending with the red marking on the thread.

Rik wrote:

“You are likely to know the ‘Travelling Salesman Problem’ (TSP).  For those who do not:  the TSP is the problem of finding the shortest path between a number of locations.  The salesman may visit each location once.  The TSP is an NP-complete problem.

Rather than the shortest path, in this puzzle you have to deal with the ‘Lazy Salesman’.  He would like to take the longest path visiting each location, thus minimizing the number of clients he can visit during one working day.”