为什么我的二进制搜索使用这么多比较?

def binary_search(sortedlist,target,comparisons):
start = 0
end = len(sortedlist) - 1


while(end - start >= 0):
    mid = (start + end)//2
    comparisons += 2
    if(target < sortedlist[mid]):
        comparisons -= 1
        end = mid - 1
    elif(target > sortedlist[mid]):
        start = mid + 1
    else:
        return target, comparisons
return False, comparisons

它基本上与这里关于二进制搜索的其他帖子相同,但出于某种原因,它使用了太多的比较。

from classes import GeneList
## Uncomment the following line to be able to make your own testing Genes
# from classes import Gene, Genome

def binary_search(sortedlist, target, comparisons):
    reducedlist = sortedlist

    while len(reducedlist) > 1:
        mid = len(reducedlist) // 2
        comparisons += 1
        if target < reducedlist[mid]:
            reducedlist = reducedlist[:mid]
        else:
            reducedlist = reducedlist[mid:]

    comparisons += 1
    if reducedlist[0] == target:
        return reducedlist[0], comparisons
    else:
        return False, comparisons


def genetic_similarity_binary(first_genome, second_genome):
    """ This function takes two Genome objects, and returns a GeneList
    and an integer. The GeneList is of all genes that are common
    between first_genome and second_genome, while the integer is
    how many comparisons it took to find all the similar genes.
    Hint: it might pay to define a helper function.
    """
    comparisons = 0
    similar_list = GeneList()
    for target in first_genome:
        result, comparisons = binary_search(second_genome, target, comparisons)
        if result:
            similar_list.append(result)
    return similar_list, comparisons

你不必做中间检查