RecursionError：与进行二分搜索相比，超出了最大递归深度

Question

这是使用python的字典程序。但我发现了这样的错误。我想知道我看到的原因..如果你知道，请问我。这是我得到的错误：$ read datafile.txt$ size176050$ find YesterdayTraceback (most recent call last):  File "C:/Users/LG/PycharmProjects/alg1/lesson1.py", line 55, in <module>    word_index = binarysearch(words,word,0,len(words)-1)  File "C:/Users/LG/PycharmProjects/alg1/lesson1.py", line 25, in binarysearch    return binarysearch(data, target,middle+1, end)  File "C:/Users/LG/PycharmProjects/alg1/lesson1.py", line 23, in binarysearch    return binarysearch(data,target,begin,middle-1)  File "C:/Users/LG/PycharmProjects/alg1/lesson1.py", line 23, in binarysearch    return binarysearch(data,target,begin,middle-1)  File "C:/Users/LG/PycharmProjects/alg1/lesson1.py", line 23, in binarysearch    return binarysearch(data,target,begin,middle-1)  [Previous line repeated 994 more times]  File "C:/Users/LG/PycharmProjects/alg1/lesson1.py", line 13, in binarysearch    if begin > end:RecursionError: maximum recursion depth exceeded in comparisonProcess finished with exit code 1这是我的代码：def datafile(file):    f = open(file,'rt',encoding='UTF8')    while True:        line = f.readline()        if not line:            break        if line == '\n':            continue        lines.append(line.split('\n')[0])    return linesdef binarysearch(data,target,begin,end):    if begin > end:        if data[end]:  #"end" index's front data exist              return end        else:            return -1    else:        middle = int(begin+end/2)        if data[middle] == target:            return middle        elif data[middle] > target:            return binarysearch(data,target,begin,middle-1)        else:            return binarysearch(data, target,middle+1, end)if __name__=="__main__":    lines = []  # all list    words = []  # list that all words is changed to lower    pos = []  # word's pos list

Answer 1

你的二分搜索算法有错误：

middle = int(begin+end/2)

由于除法优先于加法，因此不会计算中间位置。它可能导致middle变得大于end，如果data[middle] > target那么下一个间隔将在下一次递归调用中更大。这会导致无限递归。

更正为：

middle = int((begin+end)/2)

或者干脆：

middle = (begin+end)//2