求数组的子数组之和的最大值

《编程之美》的2.14中抛出了这么一道题。我的解法如下：

#!/usr/bin/env python

def getMaxSubset(data):
    if len(data)==0:
        return

    curSum = maxSum = data[0]
    i = 1
    while i < len(data):
        
        if curSum<=0:
            curSum = data[i]
        else:
            curSum+=data[i]

        if curSum>=maxSum:
            maxSum = curSum
        i+=1

    return maxSum



a1 = [-2, 5, 3, -6, 4, -8, 6]
a2 = [-2, 3, -4]
a3 = [1, -2, 3, 5, -3, 2]
a4 = [0, -2, 3, 5, -1, 2]
a5 = [-9, -8, -6, -5, -2]
a6 = [0, 0, 0, 0]
a7 = [-2,-3, 4,5,-2,6]

print getMaxSubset(a1)
print getMaxSubset(a2)
print getMaxSubset(a3)
print getMaxSubset(a4)
print getMaxSubset(a5)
print getMaxSubset(a6)
print getMaxSubset(a7)

输出为：

8
3
8
9
-2
0
13

这样只需要扫描一遍数组，时间复杂度为O(N).