Description
INTRODUCTION
The HAMILTONIAN PATH PROBLEM is a classic computer science problem: Given a graph and two vertices i and j, determine whether there is a path from i to j in the graph that visits each vertex in the graph exactly once. Now, this problem is well-known to be NP-complete.
I have written a solution to this problem (Hamiltonian_Path.cc) that uses the next_permutation function in C++ to generate all of the permutations (tours) of the ver-tices that start at vertex i and end in vertex j. This program will find a Hamiltonian Path, if it exists. Otheriwse, it will say that no such path exists. However, this program is painfully slow. On a small graph (small_graph.dat) with 5 vertices, it finds the the tour 2 0 1 3 4 from 2 to 4 in much less than a second. But, on a bigger graph (big.dat) with 13 vertices, it takes over one minute to find a solution. On bigger graphs (bigger.dat and biggest.dat), it takes much longer to solve.
For example, on input
|
5 |
2 |
4 |
|
|
0 |
:124 |
||
|
1 |
:0234 |
||
|
2 |
: 0 |
1 3 |
|
|
3 |
: 1 |
2 4 |
|
|
4 |
: 0 |
1 3 |
|
The output of the program should be “Tour = 2 0 1 3 4”.
Your task is to make this code faster using parallel computing.
Modify Hamiltonian_Path.cc using OpenMP so that
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Your modified program still produces the correct results, and
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It is at least 75% efficient on bigger.dat on a machine with 4 cores/processors.
