求nums的动态和

示例：

输入：[1,2,3,4]

输出：[1,3,6,10]

class Solution(object):
    def runningSum(self, nums):
        a=[0]*len(nums)
        for i in range(len(nums)):
            a[i]=sum(nums[:i+1])
        return a

a=Solution()
print(a.runningSum([1,2,3,4]))