I am interested in the following version of TSP:Assumption: TSP where the distances are non-negative. We know the algorithm A which computes the optional solution for such instances of TSP.Task: State an algorithm that uses the algorithm A and computes an optimal solition for instances where negative distances are allowed. 
Traveling salesman problem - negative distances allowed
complexity theory;np complete;traveling salesman
Hint: Every TSP tour has the same number of edges. Use this to modify the weights in the graph in a way which affects all TSP tours in the same way.