求数组最大子数组之和

#用来获得最大子数组之和定义成方法也方便后面的单元测试
def max(a):
    sum = max = 0
    for i in range(len(a)):
        sum += a[i]
        if sum < 0:
            sum = 0
        if max < sum:
            max = sum
    if max == 0:#说明a数组内全是负数
        max = a[0]
        for i in range(1,len(a)):
            if max < a[i]:
                max = a[i]
    return max

import unittest
from 数组的最大子数组之和.maxarray import max
class TestDemo(unittest.TestCase):
    def test_out_1(self):
        a = [1,-2,3,-4,5]
        self.assertEqual(max(a),5)
    def test_out_2(self):
        a = [-5,-1,-3,-6,-8]
        self.assertEqual(max(a),-1)

if __name__ == ‘__main__‘:
    unittest.main()