python 算法 一

• 二分查找算法

def list_search(l,v):
    left = 0
    right = len(l) -1
    while left <= right:
        mid = (left + right) // 2
        if l[mid] == v:
            return mid
        elif l[mid] < v:
            left = mid +1
        else:
            right = mid -1
    else:
        return None
l = list(range(100))
s = list_search(l,50)
print(s)