Python Two-point find detailed

Let's start with an example.

#!/usr/bin/env python import sys   def search2 (a,m): Low   = 0 High    = Len (a)-1 while    (Low <= High):     mi D = (low + high)/2     midval = A[mid]        if midval < m: Low       = mid + 1      elif midval > M: High       = mid-1< C10/>else:       print mid        return mid    print-1   return-1  if __name__ = = "__main__":   a = [Int (i) For I in list (sys.argv[1])]   m = int (sys.argv[2])   

Run:

administrator@ubuntu:~/python$ Python test_search2.py 123456789 4

3

Note:

1. ' __ ': Because Python's class members are public and publicly accessible public, there is a lack of proprietary private properties like the Orthodox object-oriented language.
So just use __ to simulate the private properties. These __ properties are often used internally and are usually not rewritten. And not read.
Add 2 underline purpose, one is not and common public attribute duplicate name conflict, second, not let the object user (non-developer) arbitrary use.
2.__name__ = = "__main__" indicates that the program script is executed directly.
If not equal to means that the script was introduced with import by another program. Its __name__ property is set to the module name

Python uses two-point search to find the subscript for a number

To consider the case of duplicate numbers

Class solution (Object):  def searchrange (self, Nums, target): ""    "    : Type Nums:list[int]    : type target: int    : Rtype:list[int] "" "    def binary_search (start,end,value): While      end>=start:        mid = (start +end)//2        Print (mid)        if nums[mid]>target:          end = Mid-1        elif nums[mid]
 
  
   
  =start and Nums[mid+value] = = target:              end = Mid+value            else:              return mid          else:            if Mid+1<=end and Nums[mid+value] = = Target:              start = Mid+value            else:              return mid       return-1    a=binary_search (0, Len (nums) -1,-1)    B=binary_search (0,len (nums) -1,1)    return [a,b]a = solution () L = [2,2]print (A.searchrange (l , 2))
 
  

The definition of the binary algorithm is not more said, Baidu a bit to know (support homemade laughter)

Import sys Source = [1,2,3,4,5,6,7,8,9,10] #must is in order des = Int (sys.argv[1]) low = 0 High = len (source)-1 Targeti  Ndex =-1 print "des=", des while low <= high:   middle = (low + high)/2   if des = = Source[middle]:     targetindex = Middle     break   elif des < Source[middle]: High     = middle-1     print "Middle element[index=", Middle, ", Value= ", Source[middle],"] is bigger than DES, continue search from[", Low," to ", High,"] "   else: low     = middle + 1     

Finally in sharing a

' filename--binarysearch.py '  src = []  def binarysearch (Low, high, Target, *src):   ' Two-point lookup ' while low   <=  High:     mid = (low + high)//2     midval = Src[mid]     if target < midval: High       = mid-1     elif target > Midval: Low       = mid + 1     else:       return mid     binarysearch (low, high, Target, *src)  print (' please Input number: ') for number in range:   src.append (int (input (' Num%d: '% number))  sortlist = tuple (src) 
  key = Int (input (' Please input key: ')] location = BinarySearch (0, Len (SRC)-1, Key, *sortlist)  if location! = None :   print (' Find target at%d '% (location + 1)) Else:   

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