Python common simple algorithms, binary lookup, bubble sort, array flipping, etc.

1, binary search: Mainly used for querying a large number of elements of the list, the use of binary search, take the median value, size comparison, can improve efficiency

1 #binary lookup, used to query a value in a larger list of data, taking into account that the element is more, simple traversal will cause memory pressure is too large, consider the use of binary search2 #the key to binary lookup is to query the middle value, compare the value you want to find with the median, and then determine the direction of the lookup3 defBinary_search (data_source,find_n):4     #take the median number5Mid=int (len (data_source)/2)6 7     ifLen (data_source) >=1:8         ifData_source[mid]>find_n:#The median is greater than the number to find, the number to find is in the left half, and the binary algorithm is called to find9 Binary_search (data_source[:mid],find_n)Ten         elifData_source[mid]<find_n:#The median is less than the number to find, the number to find is in the right half One Binary_search (data_source[mid:],find_n) A         Else:#The median is equal to the number to find -             Print("found:", Data_source[mid]) -  the     Else: -         Print("not found") -  -  + if __name__=="__main__": -Data=list (Range (1,100000)) +Binary_search (data,88888)

2. Generate a 2-D array of 5*5 and rotate it clockwise by 90 degrees

1 #algorithm Basics: Generate a 4*4 2-d array and rotate it 90 degrees clockwise2 3Array=[[col forAo.inchRange (5)] forRowinchRange (5)]#initialize an array of 4x44 #output array to view the format of the array before rotation5  forRowincharray:6     Print(Row)7 "' Analysis8 before the array is rotated9 [0, 1, 2, 3]Ten [0, 1, 2, 3] One [0, 1, 2, 3] A [0, 1, 2, 3] - " " - " " the after the array is rotated, it rotates 90 degrees clockwise, and by contrast, the first row element and the element position of the first column are exchanged each time . - that is to form part of the rotation, and so on, to achieve the final rotation - [0, 0, 0, 0] - [1, 1, 1, 1] + [2, 2, 2, 2] - [3, 3, 3, 3] + " " AName="split line before and after rotation" at Print(Name.center (60,"*")) -  forI,rowinchEnumerate (Array):#go through the line first. -     #print (I,row) -      forIndexinchRange (I,len (row)):#Gets the subscript for each row of elements, and each time the loop shrinks the extent of the adjustment -Temp=array[i][index]#Get -array[i][index]=Array[index][i] inarray[index][i]=Temp -      forRinchArrayPrint(R) to     Print("------One loop---------")

3, bubble sort, the tuples in a group of lists are arranged from small to large, and each inner loop moves only one element

1 #bubble sort, which arranges tuples in a set of lists in order from small to large, with each inner loop moving one element at a time2 #bubble Sort is relatively time-consuming, and in this case, the algorithm is added to run-time calculations3 Import Time4time1=time.time ()5data = [10,4,33,21,54,3,8,11,5,22,2,1,17,13,6]6 Print("before bubbling sort:", data)7 8  forIinchRange (len (data)):#outer loop, used to traverse all the elements9      forJinchRange (len (data)-1):#The inner loop, which is used to compare the value to the element after it, with each loop changing only the position of one valueTen         ifData[j]>data[j+1]: Onetmp=Data[j] AData[j]=data[j+1] -data[j+1]=tmp -         Print(data) the Print("after bubbling sort:", data) -Time2=time.time (); - Print('the time spent is:', time2-time1)

Python common simple algorithms, binary lookup, bubble sort, array flipping, etc.