Maximum Subarray Python

Given an integer array nums, find the contiguous subarray (containing at least one number) which has the largest sum and return its sum.

Example:

Input: [-2,1,-3,4,-1,2,1,-5,4],
Output: 6
Explanation: [4,-1,2,1] has the largest sum = 6.

Follow up:

If you have figured out the O(n) solution, try coding another solution using the divide and conquer approach, which is more subtle.

Greedy Approach:

class Solution:
    def maxSubArray(self, nums: List[int]) -> int:
        if nums is None:
            return None        maxValue = nums[0]
        maxSubArrayValue = nums[0]
        for i in range(1, len(nums)):
            maxValue = max(nums[i], maxValue + nums[i])
            maxSubArrayValue = max(maxValue, maxSubArrayValue)
        return maxSubArrayValue

Time Complexity : O(n)
Space Complexity : O(1)