PHP Program for Maximum Equilibrium Sum in an Array

<?php
// PHP program to find
// maximum equilibrium sum.

// Function to find
// maximum equilibrium sum.
function findMaxSum($arr, $n) {
    $res = PHP_INT_MIN;
    for ($i = 0; $i < $n; $i++) {
        $prefix_sum = $arr[$i];
        for ($j = 0; $j < $i; $j++) {
            $prefix_sum += $arr[$j];
        }

        $suffix_sum = $arr[$i];
        for ($j = $n - 1; $j > $i; $j--) {
            $suffix_sum += $arr[$j];
        }

        if ($prefix_sum == $suffix_sum) {
            $res = max($res, $prefix_sum);
        }
    }
    return $res;
}

// Driver Code
$arr = [-2, 5, 3, 1, 2, 6, -4, 2];
$n = count($arr);
echo findMaxSum($arr, $n);

?>

<?php
// PHP program to find maximum equilibrium sum

// Function to find maximum equilibrium sum.
function findMaxSum($arr, $n) {
    
    // Array to store prefix sum.
    $preSum[$n] = [];

    // Array to store suffix sum.
    $suffSum[$n] = [];

    // Variable to store maximum sum.
    $ans = PHP_INT_MIN;

    // Calculate prefix sum.
    $preSum[0] = $arr[0];
    for ($i = 1; $i < $n; $i++) {
        $preSum[$i] = $preSum[$i - 1] + $arr[$i];
    }

    // Calculate suffix sum and compare
    // it with prefix sum. Update ans
    // accordingly.
    $suffSum[$n - 1] = $arr[$n - 1];
    if ($preSum[$n - 1] == $suffSum[$n - 1]) {
        $ans = max($ans, $preSum[$n - 1]);
    }

    for ($i = $n - 2; $i >= 0; $i--) {
        $suffSum[$i] = $suffSum[$i + 1] + $arr[$i];
        if ($suffSum[$i] == $preSum[$i]) {
            $ans = max($ans, $preSum[$i]);
        }
    }

    return $ans;
}

// Driver Code
$arr = [-2, 5, 3, 1, 2, 6, -4, 2];
$n = sizeof($arr);
echo findMaxSum($arr, $n);

?>