Question

class index(object):

    def __init__(self,low,high,total):
        self.low = low
        self.high = high
        self.total = total
    def printing(self):
        print "Low:",self.low
        print "High:",self.high
        print "Total:",self.total

def max_crossing_subarray(A,low,mid,high):
    sum, left_sum = 0, -10000000       # Better limit for left_sum
    left_max = mid
    for i in xrange(mid-1,low-1,-1):
        sum += A[i]
        if sum > left_sum :
            left_sum = sum
            left_max = i

    sum, right_sum = 0, -10000000      # Better limit for right_sum
    right_max = mid
    for i in xrange(mid,high):
        sum += A[i]
        if sum > right_sum:
            right_sum = sum
            right_max = i

    total = left_sum + right_sum
    cross_sub = index(left_max,right_max,total)
    return cross_sub

def max_subarray(A,low,high):

    if low >= 0 and high < len(A):
        base = index(low,high,A[low])
        if high == low :
            return base
        else:
            mid = ( high + low )/2
            left = max_subarray(A,low,mid)
            right = max_subarray(A,mid+1,high)
            cross = max_crossing_subarray(A,low,mid,high)

        if left.total >= right.total and left.total >= cross.total:
            return left
        elif right.total >= left.total and right.total >= cross.total:
            return right
        else:
            return cross

def main():

    print "Enter a sequence:"
    A = map(int , raw_input().split())
    result = max_subarray(A,0,len(A))
    result.printing()

为了确定最大子阵列，我写了上面的代码。我得到的问题是，在编译时它显示：

我是Python的初学者，我真的很喜欢这里的一些指导。

谢谢。

编辑：

异常的完整回溯日志：

Traceback (most recent call last):
  File "main2.py", line 59, in <module>
    main()
  File "main2.py", line 57, in main
    result.printing()
AttributeError: 'NoneType' object has no attribute 'printing'

Answer 1

编辑：在主要部分中，您将提供max_subarray函数len(A)函数，该函数指出A列表中有多少元素。相反，你应该从中减去一个，因为（我认为）的意图是给出寻找子阵列的范围，因此A[len(A)]是不正确的。

result = max_subarray(A, 0, len(A) - 1)

此外，我不确定您的算法是否正确，请检查如果要增加序列会发生什么。

Python中的Max SubArray确定

1 个答案: