]0. Create package prog09. Download Sorter.java, SortTest.java, and
ExternalSort.java.
1. Implement isSorted. Use compareTo on every pair of adjacent items.
2. Implement sameContents using HashMap.
3. Finish implementing InsertionSort and test.
4. Ditto HeapSort. (Uncomment line in tests method.)
5. Ditto QuickSort.
HOMEWORK
6. Ditto MergeSort.
7. In main, call tests with powers of 10 from 10,000 to 10,000,000.
Make sure your Sorter implementations have the correct O().
8. Write the merge method in ExternalSort. Test on number.txt and
then make your own file with different lengths to make sure you have
it right.
