Function implementing Kadane's Algorithm (array contains at least one positive number) - Java Algorithm

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Description

Function implementing Kadane's Algorithm (array contains at least one positive number)

Demo Code


public class kadane_Algorithm 
{
  public static int kadane(int input[], int n) // 
  {//from  w  w w . ja v  a2s  . c  om
    int current_max = 0;
    int max_so_far = 0;
    
    for(int i = 0; i < n; i++)
    {
      current_max = Math.max(0, current_max + input[i]);
      max_so_far = Math.max(max_so_far, current_max);
    }

    return max_so_far; // Maximum subarray sum
  }


  public static void main(String[] args) 
  {
    int n, max_subarray_sum;
    int input[] = { -2, 1, -6, 4, -1, 2, 1, -5, 4 }; // Input array
    n = input.length; // Size of array

    int flag = 0; // Flag variable to check if all the numbers in array are negative or not
    int largest_in_negative = input[0];
    // Smallest_negative variable will store the maximum subarray sum if all the numbers are negative in array

    for(int i = 0; i < n; i++) // Scanning each element in array
    {
      if(input[i] >= 0) // If any element is positive, kadane's algo can be applied
      {
        flag = 1;
        break;
      }

      else if(input[i] > largest_in_negative) // If all the elements are negative, find the largest in them
        largest_in_negative = input[i];
    }

    if(flag == 1) // Kadane's algo applicable
         max_subarray_sum = kadane(input, n);
    else
         max_subarray_sum = largest_in_negative; // Kadane 's algo not applicable,

    System.out.println("Maximum Subarray Sum is " + max_subarray_sum);
  }
  
}

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