[LC] 53. Maximum Subarray

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.

Time:O(N)
Space:O(N)

 1 class Solution:
 2     def maxSubArray(self, nums: List[int]) -> int:
 3         if nums is None or len(nums) == 0:
 4             return
 5         
 6         sum_arr = [0] * len(nums)
 7         sum_arr[0] = nums[0]
 8         max_res = nums[0]
 9         for i in range(1, len(nums)):
10             if sum_arr[i - 1] > 0:
11                 sum_arr[i] = nums[i] + sum_arr[i - 1]
12             else:
13                 sum_arr[i] = nums[i]
14             max_res = max(max_res, sum_arr[i])
15         return max_res