Performance of the serial implementations
The run-times of the three serial implementations are shown in Table 6.7. The input digraph contained 15 vertices (including the hometown), and all three algorithms vis-ited approximately 95,000,000 tree nodes. The first iterative version is less than 5% faster than the recursive version, and the second iterative version is about 8% slower than the recursive version. As expected, the first iterative solution eliminates some of the overhead due to repeated function calls, while the second iterative solution is slower because of the repeated copying of tour data structures. However, as we’ll see, the second iterative solution is relatively easy to parallelize, so we’ll be using it as the basis for the parallel versions of tree search.