programming-for-dummies

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Using Merge Sort
Figure 1-10 shows how merge sort works.
Because the merge sort algorithm successively divides a list in half, merge
sort needs to create temporary data structures (such as arrays) to store
data while it divides and merges values. When sorting a small list, creating a
temporary data structure is simple, but when sorting a large list, creating a
temporary large data structure can gobble up memory.
In Perl 5.8, the default sorting algorithm is merge sort. In earlier versions of
Perl, the default sorting algorithm was quick sort.
32 9 74 21
14 97 50 45 Original, unsorted list
32 9 74 21
14 97 50 45
32 9 74 21 14 97 50 45
32 9 74 21 14 97 50 45
Figure 1-10:
Merge sort
breaks a
long list into
several
smaller
ones and
then merges
these back
into a longer
list.
9 32 21 74
9 21 32 74
9 14 21 32
14 97
14 95
45 50 74 97
50
45
97
50
Final sorted list