5. 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


Solution 1


def maxSubArray(self, nums: List[int]) -> int:
    max_sum = nums[0]
    sub_sum = nums [0]
    for i in range(1, len(nums)):
        sub_sum = max(nums[i],nums[i] + sub_sum)
        max_sum = max(max_sum,sub_sum)
    return max_sum

Solution 2


def maxSubArray(self, nums: List[int]) -> int:
    maxSub = nums[0]
    curSum = 0
     for i in nums:
        if curSum < 0:
            curSum = 0
        curSum += i
        maxSub = max(maxSub, curSum)
     return maxSub