算法学习之：python 实现折半查找（binary search）

代码

• 折半查找要求序列已经是有序的。

def binsearch(a,k):
    ## 对于已经排好序的序列
    alen = len(a)
    low = 0
    hi = alen - 1
    while low <= hi:
        mid = (low + hi) // 2
        if a[mid] == k:
            return mid
        elif a[mid] > k:
            hi = mid -1
        else:
            low = mid + 1
    return -1
if __name__ == '__main__':

    a = [1,2,3,4,5,6,7]
    print(binsearch(a,6))