Python Eight sort Quick sort

A, Quick Sort

1) Set two variables I, J, when sorting begins: I=0,j=n-1;2) takes the first array element as the key data, assigns the value to Key, i.e. Key=A[0];3) forward search from J, that is, after the start of a forward search (j--), find the first less than KeyValue a[j], a[j] and A[i] interchange, 4) from I start backward search, that is, to start backward search (i++), to find the first one greater than KeyA[i], will a[i] and A[j] interchange;

5) Repeat 3rd, 4, until i=j, (3,4 step, did not find the matching criteria, that is, 3 a[j] is not less than key, 4 A[i] is not larger than the time of the key change J, I value, so j=j-1,i=i+1, until found. Locate the value that matches the condition, and the J pointer position does not change when I exchange it. In addition, I==J this process must be exactly when the i+ or J completes, at which time the loop ends).

As a list:

　　LST =[6,1,2,7,9,3,4,5,10,8]

[6, 1, 2, 7, 9, 3, 4, 5, 10, 8]
Start right-to-left to move the first time
When J moves to 5 this time lst[j] is less than key6
I j Value Interchange
[5, 1, 2, 7, 9, 3, 4, 6, 10, 8]
Start moving from left to right for the first time
When I moves to 7 this time lst[i] is greater than key6
I j Value Interchange
[5, 1, 2, 6, 9, 3, 4, 7, 10, 8]
Start from right to left to move the second time
When J moves to 4 this time lst[j] is less than key6
I j Value Interchange
[5, 1, 2, 4, 9, 3, 6, 7, 10, 8]
Move from left to right to start the second time
When I moves to 9 this time lst[i] is greater than key6
I j Value Interchange
[5, 1, 2, 4, 6, 3, 9, 7, 10, 8]
Move the third time from right to left
When J moves to 3 this time lst[j] is less than key6
I j Value Interchange
[5, 1, 2, 4, 3, 6, 9, 7, 10, 8]
At this point 6 is in the middle.

LST is divided into two parts

Left [5, 1, 2, 4, 3]

Right [9, 7, 10, 8]

Re-follow the just sort method

Will get results
Left [3, 1, 2, 4, 5]

Right [8, 7, 9, 10]

Continue sorting

..... (recursive)

Implementation method:

Process oriented:

#-*-CODING:GBK-*-__author__='Hzq'LST= [6,1,2,7,9,3,4,5,10,8]i=0j=len (LST)-1Key=Lst[0]Print(LST)Print("start right-to-left to move the first time") whileLst[j]>=key andJ>i:j-=1Print("when J moves to {} at this time lst[j] is less than key{}". Format (lst[j],key))Print("I J Value Interchange") Lst[i],lst[j]=Lst[j],lst[i]Print(LST)Print("start moving from left to right for the first time") whileLst[i]<=key andJ>i:i+=1Print("when I moves to {} at this time lst[i] is greater than key{}". Format (lst[i],key))Print("I J Value Interchange") Lst[i],lst[j]=Lst[j],lst[i]Print(LST)Print("start from right to left to move the second time") whileLst[j]>=key andJ>i:j-=1Print("when J moves to {} at this time lst[j] is less than key{}". Format (lst[j],key))Print("I J Value Interchange") Lst[i],lst[j]=Lst[j],lst[i]Print(LST)Print("move from left to right to start the second time") whileLst[i]<=key andJ>i:i+=1Print("when I moves to {} at this time lst[i] is greater than key{}". Format (lst[i],key))Print("I J Value Interchange") Lst[i],lst[j]=Lst[j],lst[i]Print(LST)Print("move the third time from right to left") whileLst[j]>=key andJ>i:j-=1Print("when J moves to {} at this time lst[j] is less than key{}". Format (lst[j],key))Print("I J Value Interchange") Lst[i],lst[j]=Lst[j],lst[i]Print(LST)

Object-oriented:

#-*-CODING:GBK-*-__author__='Hzq'LST= [6,1,2,7,9,3,4,5,10,8]defMinddle_index (Lst,low,high): Start_index=low#far leftEnd_index=high#left and right side    ifStart_index<end_index:#precondition right greater than leftkey=Lst[start_index] #设置参照key whileEnd_index>Start_index: whileLst[end_index]>=key andEnd_index>Start_index:end_index-=1Lst[start_index],lst[end_index]=Lst[end_index],lst[start_index] whileLst[start_index]<=key andEnd_index>Start_index:start_index+=1Lst[start_index],lst[end_index]=Lst[end_index],lst[start_index]#Loop Sort, recursiveMinddle_index (lst,low,start_index-1)#left lst sorted againMinddle_index (Lst,end_index+1,high)#right lst again sortMinddle_index (Lst,0,len (LST)-1)Print(LST)

Python Eight sort Quick sort