CA 10 - Kadanes Algorithm

 Kadane's Algorithm

You are given an integer array arr[]. You need to find the maximum sum of a subarray (containing at least one element) in the array arr[]
Input: arr[] = [2, 3, -8, 7, -1, 2, 3]
Output: 11
Explanation: The subarray [7, -1, 2, 3] has the largest sum 11.

Input: arr[] = [-2, -4]
Output: -2
Explanation: The subarray [-2] has the largest sum -2.
Input: arr[] = [5, 4, 1, 7, 8]
Output: 25
Explanation: The subarray [5, 4, 1, 7, 8] has the largest sum 25.
Time Complexity: O(n)
Auxiliary Space: O(1)

CODE:

    The problem can be solved with the brute force method, of using two for loop to obtain the maximum sum array, but the time complexity will be O(n^2) but the constraint for the time complexity is O(n). Thus, we make use of the Kadane's Algorithm.

class Solution:
    def maxSubarraySum(self, arr):
        n = len(arr)
        currmax = arr[0]
        globalmax = arr[0]
        for i in range(1,n):
            currmax = max(arr[i],arr[i]+currmax)
            globalmax = max(currmax,globalmax)
        return globalmax

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