二分法查找

1.用函数来进行二分查找:

  lst = [11,22,33,44,55,66,77,88,99,123,234,345,456,567,678,789,1111]

def run(left,right,n,count):
    middle=(left+right)//2
    if n >lst[middle]:
        left=middle+1
    elif n < lst[middle]:
        right=middle-1
    else:
        return (middle,'找到了,共计查找了%s次' % count)
    return run(left,right,n,count+1)
print(run(0,len(lst)-1,11,1))

2.普通方法:

lst = [11,22,33,44,55,66,77,88,99,123,234,345,456,567,678,789,1111]
n=11     #要查询的数
left=0
right=len(lst)-1
count=0
while left <= right:
    count+=1
    middle = (left + right) // 2
    if n > lst[middle]:
        left=middle+1
    elif n < lst[middle]:
        right=middle-1
    else:
        print('索引为%s,共计查询了%s次' % (middle,count))
        break
else:
    print('不存在')