Python sorting algorithm

Do not feel that there have been six months have not written, time is really easy to neglect, this half a year after a spring festival, to Lhasa Travel. The job is also very busy, did not carry out systematic study and summary.

This year began to calm down to start learning from the basic, mainly divided into three parts, algorithm, linear algebra, probability statistics.

The first learning algorithm, in Python language implementation, mainly in order to understand the idea, after all, there are many wheels off the shelf. The next study of linear algebra and probability statistics, mainly through the two books in Japan, the implementation of programming from the numerical analysis began to learn, perhaps to use Matlab.

Algorithm, learning the book is "Python algorithm tutorial", covering the knowledge of the whole, the shortcomings of the need to have a certain foundation, I read the book first, and read the "Programmer's Math" (this looks too easy), and then the inside of the idea has a perceptual understanding, but specific to the algorithm, or it is difficult to write out, So want to put the book involved in the problem, code, all to achieve their own, as a review.

Starting with the simplest sort, you can start from scratch to the end, or in turn, you can write recursion or write loops.

1. From the beginning to the end, is to choose the small, put to the front.

Recursive

1 defSort_f (seq,i):2     ifi==0:3         return4Sort_f (seq,i-1)5j=I6      whileJ>0 andSeq[j-1]>Seq[j]:7Seq[j],seq[j-1]=seq[j-1],seq[j]8J-=19 Tenseq = [9,8,7,6,5,4,3,2,1] One  A------------------------------------------------------- -  ->>> sort_f (Seq,len (seq)-1) the>>>seq -[1, 2, 3, 4, 5, 6, 7, 8, 9]

Cycle

def sort_f2 (seq):      for inch range (len (seq)):          for inch Range (I,len (seq)):             if seq[j]<seq[i]:                seq[i],seq[j]=seq[j],seq[i]

2. From the end of the tail, is to choose the largest, put in the last

Recursive

def sort_e (seq,i):     if i==0:        return    sort_e (seq,i-1)    = I      while  and Seq[j]<seq[j-1]:        seq[j],seq[j-1]=seq[j-1],seq[j]        J-=1

Recursive or write like this

def Sort_ee (seq,i):     if i==0:        return    maxj=i    for in Range (i):         if seq[j]>SEQ[MAXJ]:            maxj=J    Seq[i],seq[maxj]=seq[maxj],seq[i ]    Sort_ee (seq,i-1)

Cycle

def sort_e2 (seq):    i=len (seq)-1     while i>0:        for in  Range (i):            if seq[j]>  Seq[i]:                seq[i],seq[j]=Seq[j],seq[i]        i-=1

Python sorting algorithm