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Maximum Subarray

Problem Statement​

Given an integer array nums, find the subarray which has the largest sum and return its sum.

Leetcode link

Examples​

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 <= 105
  • 104 <= nums[i] <= 104

Code​

Python3 Code
class Solution:
    def maxSubArray(self, nums: List[int]) -> int:
        curr , maxi = float("-inf"),nums[0]

        for x in nums:
            curr = max(x,curr+x)
            #current greedily chooses
            # between either the current array value or
            #the previous curr+ the current arr value
            #that is the current subarrray sum
            maxi = max(maxi,curr)
            #print(curr,maxi)
        return maxi