python - 相比之下，是否超出了最大递归深度？

Question

开始学习python，这是我尝试过的最大和子数组。最终得到“相比之下超出了最大递归深度”。我的算法对我来说似乎没问题。如果我做错了什么，请帮助我。

import sys
import math
def maxtuple(lss,rss):
    if lss[2] > rss[2]:
        return lss
    else:
        return rss
def crosssubarray(A, start, mid, end):
    ls=rs=-sys.maxsize
    maxleft=0
    maxright=0
    sum = 0;
    for i in reversed(range(start, mid)):
        sum = sum + A[i]
        print(i)
        if sum > ls:
            ls = sum
            maxleft = i
    sum = 0
    for i in range(mid+1, end):
        sum = sum+ A[i]
        if sum > rs:
            rs = sum
            maxright = i
    return (maxleft, maxright, ls+rs)

def maxsubarray(A,start,end):
    if start == end:
        return (start,end,A[start])
    else:
        mid = (start+end)/2
        lss = maxsubarray(A, start, mid)
        rss = maxsubarray(A, mid+1, end)
        css = crosssubarray(A, start, mid, end)
        maxsub = maxtuple(lss,rss)
        maxall = maxtuple(maxsub, css)
        return maxall

A = [13,-3,-25,20,-3,-16,-23,18,20,-7,12,-5,-22,15,-4,7]
print(maxsubarray(A,0,15))

Answer 1

你的问题出在这个函数上:

def maxsubarray(A,start,end):
    if start == end:
        return (start,end,A[start])
    else:
        mid = (start+end)/2
        lss = maxsubarray(A, start, mid)
        rss = maxsubarray(A, mid+1, end)
        css = crosssubarray(A, start, mid, end)
        maxsub = maxtuple(lss,rss)
        maxall = maxtuple(maxsub, css)
        return maxall

准确地说，是前 5 行。在 python 2.x 中“工作”(不知道您的预期结果)的原因是因为 / 用于楼层划分，而在 python 3.x 中 / 是用于浮点除法。由于浮点舍入误差，start 很可能永远不会等于 end。

---

如果您想要整数除法，则可以将 / 替换为 //。

这样做，错误将消失并返回(8, 10, 32)