Given an integer array nums, find the contiguous subarray (containing at least one number) which has the largest sum and return its sum.
def maxSubArray(self, nums: 'List[int]') -> 'int':
n = len(nums)
curr_sum = max_sum = nums[0]
for i in range(1, n):
curr_sum = max(nums[i], curr_sum + nums[i])
max_sum = max(max_sum, curr_sum)
return max_sum