Hackerrank 30 Days of Code Day 11: 2D Arrays

30-days-of-code-day-11

<?php
/*
test 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
*/

$handle = fopen ("php://stdin","r");
$arr = array();
$sum_list = array();
$top_bottom_count = 3;

// get contents
for($arr_i = 0; $arr_i < 6; $arr_i++) {
   $arr_temp = fgets($handle);
   array_push($arr, explode(" ",$arr_temp));
}

// loop through contents
for ($i=0; $i < count($arr) - 2; $i++){
    for($j=0; $j <= count($arr[$i])-$top_bottom_count; $j++){
        array_push($sum_list, getSum($arr, $i, $j, $top_bottom_count));
    }
}


// print sum
echo max($sum_list);

function getSum($arr, $row, $col, $count){
    $sum = 0;
    for($i=0; $i<$count; $i++){
        $sum += $arr[$row][$col+$i];
        $sum += $arr[$row+2][$col+$i];
    }
    $sum += $arr[$row+1][$col+1];
    return $sum;
}
?>

Challenge Name: Day 11: 2D Arrays

Objective
Today, we're building on our knowledge of Arrays by adding another dimension. Check out the Tutorial tab for learning materials and an instructional video!

Context
Given a 6 x 6 2D Array, A:

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 A to be a subset of values with indices falling in this pattern in A's graphical representation:

a b c
  d
e f g

There are $16$ hourglasses in A, and an hourglass sum is the sum of an hourglass' values.

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