溫馨提示×
您好，登錄后才能下訂單哦！
點擊 登錄注冊 即表示同意《億速云用戶服務條款》
您好，登錄后才能下訂單哦！
這篇文章主要講解了Python二分查找算法的實現方法，內容清晰明了，對此有興趣的小伙伴可以學習一下，相信大家閱讀完之后會有幫助。
先來看個用Python實現的二分查找算法實例
import sys def search3(a,m): low = 0 high = len(a) - 1 while(low <= high): mid = (low + high)/2 midval = a[mid] if midval < m: low = mid + 1 elif midval > m: high = mid - 1 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]) search3(a,m)om/weixin.html#_labeldown
運行:
administrator@ubuntu:~/Python$ python test_search3.py 123456789 4
注:
1.'__'：由于python的類成員都是公有、公開的被存取public，缺少像正統面向對象語言的私有private屬性。
于是就用__來將就一下，模擬私有屬性。這些__屬性往往是內部使用，通常情況下不用改寫。也不用讀取。
加上2個下劃線的目的，一是不和普通公有屬性重名沖突，二是不讓對象的使用者(非開發者)隨意使用。
2.__name__ == "__main__"表示程序腳本是直接被執行的.
如果不等于表示腳本是被其他程序用import引入的.則其__name__屬性被設為模塊名
Python采用二分查找找出數字的下標
要考慮有重復數字的情況
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]<target: start="mid+1" else:="" if="" value="=-1:" mid-1="">=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
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))
</target:>二分算法的定義不在多說了
import sys source = [1,2,3,4,5,6,7,8,9,10] #must be in order des = int(sys.argv[1]) low = 0 high = len(source) - 1 targetIndex = -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 print "middle element[index=",middle,",value=",source[middle],"] is smaller than des, continue search from[",low,"to",high,"]" print "search complete, target element's index in source list is ",targetIndex
最后在分享一個
'fileName--BinarySearch.py'
src = []
def BinarySearch(low, high, target, *src):
'二分查找'
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 10 number:')
for number in range(10):
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:
print('No target!')實例補充
#!/usr/bin/python env # -*- coding:utf-8 -*- def half_search(array,target): low = 0 high = len(array) - 1 while low < high: mid = (low + high)/2 if array[mid] > target: high = mid - 1 elif array[mid] < target: low = mid + 1 elif array[mid] == target: print 'I find it! It is in the position of:',mid return mid else: print "please contact the coder!" return -1 if __name__ == "__main__": array = [1, 2, 2, 4, 4, 5]
運行結果如下：
I find it! It is in the position of: 4 4 -1 I find it! It is in the position of: 0 0 -1
看完上述內容，是不是對Python二分查找算法的實現方法有進一步的了解，如果還想學習更多內容，歡迎關注億速云行業資訊頻道。
免責聲明：本站發布的內容（圖片、視頻和文字）以原創、轉載和分享為主，文章觀點不代表本網站立場，如果涉及侵權請聯系站長郵箱：is@yisu.com進行舉報，并提供相關證據，一經查實，將立刻刪除涉嫌侵權內容。
