MPI并行解决TSP问题

* Purpose: Use iterative depth-first search and MPI to solve an instance of the travelling salesman problem. This version partitions the search tree using breadth-first search. Then each process searches its assigned subtree. There is no reassignment of tree nodes. This version also attempts to reuse deallocated tours. The best tour structure is broadcast using a loop of MPI_Bsends. * Compile: mpicc -g -Wall -o mpi_tsp main.cpp * Usage: mpiexec -n <proc count> mpi_tsp <matrix_file> * Input: From a user-specified file, the number of cities followed by the costs of travelling between the cities organized as a matrix: the cost of travelling from city i to city j is the ij entry. Costs are nonnegative ints. Diagonal entries are 0. * Output: The best tour found by the program and the cost of the tour.