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Identify and list the contiguous array sections with the highest sum total.

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Locate and present a subsection of an array with the highest possible total value
Locate and present a subsection of an array with the highest possible total value

Identify and list the contiguous array sections with the highest sum total.

Kadane's Algorithm is a popular and efficient method to find the contiguous subarray within a one-dimensional array that has the maximum sum. This algorithm runs in linear time (O(n)) and requires minimal auxiliary space (O(1)).

How Kadane's Algorithm Works

The algorithm works by scanning through the array while keeping track of the maximum sum of subarrays ending at each position. Here's a step-by-step breakdown:

  1. Initialization: Initialize two variables - and . represents the maximum sum of a subarray ending at the current index, while is the maximum sum found so far across all subarrays.
  2. Iteration: Iterate through the array. For each element, decide whether to extend the current subarray or start a new subarray from the current element, by choosing whichever is larger. Update accordingly. If exceeds , update .
  3. Tracking Subarray Boundaries (Optional): Optionally, track the start and end indexes of the maximum subarray by resetting the start index when a new subarray begins and updating the end index whenever a new maximum is found.

By deciding at each element whether to extend the current subarray or start anew, Kadane's algorithm efficiently finds the global maximum subarray sum without checking all subarrays explicitly, unlike brute force methods which have a time complexity of O(n^2).

Example Python Code Snippet

```python def maxSumSubarray(arr): maxEndingHere = arr[0] maxSoFar = arr[0] start = end = s = 0

```

This returns the maximum-sum subarray itself, not just the sum.

Key Features of Kadane's Algorithm

  • The algorithm has a time complexity of O(n), scanning the array once.
  • It uses dynamic programming by building on the solution to the problem for smaller prefixes of the array.
  • It is currently the most optimal and widely used algorithm for the maximum subarray sum problem in one-dimensional arrays.
  • The inner loop marks the ending point of the subarray.
  • The outer loop marks the starting point of a subarray.
  • The task is to print the subarray with maximum sum from a given array.

This approach is elegant because it implicitly uses the optimal substructure property: the maximum subarray ending at position i depends only on the maximum subarray ending at position i-1 and the current element, avoiding the overhead of checking every possible subarray.

[1] Brute force method: https://en.wikipedia.org/wiki/Maximum_subarray_problem#Brute_force_method [4] Kadane's Algorithm: https://en.wikipedia.org/wiki/Maximum_subarray_problem#Kadane's_algorithm [5] Dynamic programming: https://en.wikipedia.org/wiki/Maximum_subarray_problem#Dynamic_programming_method

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