Week 9

'''
This week we talk about the main idea for three sorts,
which is selection sort, merge sort, and quick sort.
Selection Sort is a simple and intuitive sorting algorithm.
First, find the smallest unsorted sequence (large) elements
stored in the collating sequence of the starting position,
and then again from the remaining unsorted elements continue
to look for the smallest (large) elements, and then sorted into
the end of the sequence. And so on until all the elements are sorted.
Merge sort, divide the list in half, sort the halves, then merge the
sorted results, i think it should be easy done by use recursion. By the way,
the efficiency of merger sort is just after quick sort, it is a stable s
sorting algorithm, generally used for general disorder, but each child is
relatively orderly sequence.
Quick sort, which is fastest in almost all case , but not the worst case.
the main idea of quick sort is choose a pivot; decide where the pivot goes
with respect to the rest of the list, repeat on the partition.
'''