在Python中可以利用bisect模塊來實現二分搜索，該模塊包含函數只有幾個：

import bisect

L = [1,3,4,5,5,5,8,10]
x = 5

bisect.bisect_left(L,x) # 3
# 在L中查找x，x存在時返回x最左側的位置，x不存在返回應該插入的位置

bisect.bisect_right(L,x) # 6
# 在L中查找x，x存在時返回x最右側的位置，x不存在返回應該插入的位置

bisect.insort_left(L,x) # [1, 3, 4, 5, 5, 5, 5, 8, 10]
# 將x插入到列表L中，x存在時插入在左側

bisect.insort_right(L,x) 
 
# [1, 3, 4, 5, 5, 5, 5, 5, 8, 10]
# 將x插入到列表L中，x存在時插入在右側

　　bisect.insort_left和bisect.insort_right貌似沒什麽差別，作用基本一致。

　　另外，bisect.bisect(L,x)與bisect_right相同，insort與insort_right相同。

　　例子：

import bisect
import random

mylist = list()
for i in range(10):
    num = random.randint(1,100)
    index = bisect.bisect_left(mylist, num)
    bisect.insort_left(mylist, num)
    
 
print(‘num ‘, str(num), ‘index ‘, str(index), ‘list ‘, mylist)
    
mylist = list()
for i in range(10):
    num = random.randint(1,100)
    index = bisect.bisect_right(mylist, num)
    bisect.insort_right(mylist, num)
    print(‘num ‘, str(num), ‘\tindex ‘, str(index), ‘\tlist ‘ ,mylist)

　　輸出：

num  72 index  0 list  [72]
num  
 
89 index  1 list  [72, 89]
num  41 index  0 list  [41, 72, 89]
num  45 index  1 list  [41, 45, 72, 89]
num  100 index  4 list  [41, 45, 72, 89, 100]
num  1 index  0 list  [1, 41, 45, 72, 89, 100]
num  69 index  3 list  [1, 41, 45, 69, 72, 89, 100]
num  4 index  1 list  [1, 4, 41, 45, 69, 72, 89, 100]
num  76 index  6 list  [1, 4, 41, 45, 69, 72, 76, 89, 100]
num  11 index  2 list  [1, 4, 11, 41, 45, 69, 72, 76, 89, 100]

num  82         index  0        list  [82]
num  39         index  0        list  [39, 82]
num  27         index  0        list  [27, 39, 82]
num  78         index  2        list  [27, 39, 78, 82]
num  9  index  0        list  [9, 27, 39, 78, 82]
num  80         index  4        list  [9, 27, 39, 78, 80, 82]
num  58         index  3        list  [9, 27, 39, 58, 78, 80, 82]
num  42         index  3        list  [9, 27, 39, 42, 58, 78, 80, 82]
num  59         index  5        list  [9, 27, 39, 42, 58, 59, 78, 80, 82]
num  50         index  4        list  [9, 27, 39, 42, 50, 58, 59, 78, 80, 82]

END 2018-11-01 23:25:37

Python學習筆記：bisect模塊實現二分搜索