Use the sorting pattern to implement insertion sort. In insertion sort, the split method always returns the value (end — 1) . This results in splitting the array into two pieces, one with a single value at the end of the array, and the other with everything else. The join method does more work. A precondition for entry into join is that the elements from a[begin] to a[end-1] will be in sorted order. The method should insert a[end] into the correct spot from a[begin] to a[end] such that sorted order is maintained. For example, if array a contains {2, 4, 6, 8, 5} where begin = 0 and end = 4 then a[end] = 5 and the method should insert the value 5 between the 4 and 6, resulting in {2, 4, 5, 6, 8} . This entails copying the 6 and 8 one element to the right, and then copying the value 5 to index 2.