Question

Pick an algorithm. Write the psuedo-code for a parallel implementation.

Answer 1

The pseudocode provided outlines a parallel implementation of the QuickSort algorithm, which includes spawning new threads to sort sub-arrays in parallel, thus optimizing performance on multi-core processors. It emphasizes the recursive nature of the QuickSort algorithm and the importance of managing shared resources and thread synchronization to avoid concurrency issues.

Step-by-step explanation:

When considering a parallel implementation algorithm, one appropriate example is the parallel version of the QuickSort algorithm, which is well-suited for sorting large datasets. The pseudocode for a parallel QuickSort might look something like this:

Parallel QuickSort Algorithm Pseudocode:

1. Procedure ParallelQuickSort(array, left, right)
2. If (left < right) Then
3. pivotIndex = Partition(array, left, right)
4. spawn a new thread to ParallelQuickSort(array, left, pivotIndex - 1)
5. ParallelQuickSort(array, pivotIndex + 1, right)
6. wait for all spawned threads to complete
7. End If
8. End Procedure
9. Procedure Partition(array, left, right)
   (Implementation of the partitioning logic specific to QuickSort)

The key concept here is that the algorithm recursively sorts sub-arrays in parallel, effectively utilizing multiple processors or cores to decrease the sorting time. It's critical to ensure that accesses to shared resources are handled to prevent issues such as race conditions. Moreover, an overhead of thread creation and synchronization must be considered when applying parallelism.