二分查找法

def bin_search(data,val):
    high = len(data)-1
    low = 0

    while low <= high: # 考虑要查询的值在列表最两端 所以 low=high
        mid = (low + high) // 2
        if data[mid] == val:
            return mid
        elif  data[mid] > val:
            high = mid-1
        else:
            if data[mid] < val:
                low = mid+1

    return


a = [x for x in range(1,5)]

print(a)
b = bin_search(a,4)