Context On 2D Array - c Programming : hackerrank problem

Given a  2D Array, :

1 1 1 0 0 0
0 1 0 0 0 0
1 1 1 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0

We define an hourglass in  to be a subset of values with indices falling in this pattern in 's graphical representation:

a b c
  d
e f g

There are  hourglasses in , and an hourglass sum is the sum of an hourglass' values.

Task
Calculate the hourglass sum for every hourglass in , then print the maximum hourglass sum.

Input Format

There are  lines of input, where each line contains  space-separated integers describing 2D Array ; every value in  will be in the inclusive range of  to .

Constraints

Output Format

Print the largest (maximum) hourglass sum found in .

Sample Input

1 1 1 0 0 0
0 1 0 0 0 0
1 1 1 0 0 0
0 0 2 4 4 0
0 0 0 2 0 0
0 0 1 2 4 0

Sample Output

19

Explanation

 contains the following hourglasses:

1 1 1   1 1 0   1 0 0   0 0 0
  1       0       0       0
1 1 1   1 1 0   1 0 0   0 0 0

0 1 0   1 0 0   0 0 0   0 0 0
  1       1       0       0
0 0 2   0 2 4   2 4 4   4 4 0

1 1 1   1 1 0   1 0 0   0 0 0
  0       2       4       4
0 0 0   0 0 2   0 2 0   2 0 0

0 0 2   0 2 4   2 4 4   4 4 0
  0       0       2       0
0 0 1   0 1 2   1 2 4   2 4 0

The hourglass with the maximum sum () is:

2 4 4
  2
1 2 4

#include <math.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include <limits.h>
#include <stdbool.h>
int sum(int r,int c,int arr[6][6])
{
int s=0;
s=arr[r][c]+arr[r][c+1]+arr[r][c+2];
s+=arr[r+1][c+1];
s+=arr[r+2][c+0]+arr[r+2][c+1]+arr[r+2][c+2];
return s;

}

int main(){
    int arr[6][6] ;  /*={{1,1,1,0,0,0},
                   {0,1,0,0,0,0,},
                   {1,1,1,0,0,0},
                   {0,0,2,4,4,0},
                   {0,0,0,2,0,0},
                   {0,0,1,2,4,0}};  */
    int smax,i,j,val;
    
    for(int arr_i = 0; arr_i < 6; arr_i++){
       for(int arr_j = 0; arr_j < 6; arr_j++){

          scanf("%d",&arr[arr_i][arr_j]);
       }
    }
    
    smax=sum(0,0,arr);

    for(i=0;i<=3;i++)
        for(j=0;j<=3;j++)
        {
            val=sum(i,j,arr);
                if(smax<val)
                    smax=val;
        }

    printf("\nMax Hour Glass=%d",smax);
    return 0;
}