finding the start and end index for a max sub array

Question

 public static void main(String[] args) {


        int arr[]= {0,-1,2,-3,5,9,-5,10};



        int max_ending_here=0;
        int max_so_far=0;
        int start =0;
        int end=0;

        for(int i=0;i< arr.length;i++)
        {
            max_ending_here=max_ending_here+arr[i];
            if(max_ending_here<0)
            {
                max_ending_here=0;
            }

            if(max_so_far<max_ending_here){

                max_so_far=max_ending_here;


            }

        }
        System.out.println(max_so_far);



    }

}

this program generates the max sum of sub array ..in this case its 19,using {5,9,-5,10}.. now i have to find the start and end index of this sub array ..how do i do that ??

Answer 1

This is a C program to solve this problem. I think logic is same for all languages so I posted this answer.

void findMaxSubArrayIndex(){          
        int n,*a;
        int start=0,end=0,curr_max=0,prev_max=0,start_o=0,i;

        scanf("%d",&n);
        a = (int*)malloc(sizeof(int)*n);
        for(i=0; i<n; i++)  scanf("%d",a+i);

        prev_max = a[0];

        for(i=0; i<n; i++){
            curr_max += a[i];
            if(curr_max < 0){
                start = i+1;
                curr_max = 0;
            }
            else if(curr_max > prev_max){
                end = i;
                start_o = start;
                prev_max = curr_max;
            }

        }

        printf("%d %d \n",start_o,end); 
}