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.

A subarray is a contiguous part of an array.

Example 1:

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

Example 2:

Input: nums = [1]
Output: 1

Example 3:

Input: nums = [5,4,-1,7,8]
Output: 23

Constraints:

• 1 <= nums.length <= 3 * 10⁴
• -10⁵ <= nums[i] <= 10⁵

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.

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class Solution:
    def maxSubArray(self, nums: List[int]) -> int:
        current_max = all_max = nums[0]
        for n in nums[1:]:
            current_max = max(n, current_max+n)
            all_max = max(all_max, current_max)
        return all_max