Given an array A of positive integers. Find the maximum sum of a subsequence such that no two numbers in the sequence should be adjacent in the array.

max_sum.php

<?php
    $arr = array(5,5,10,100,10,5);
    $n = count($arr);
    $inc = $arr[0];
    $ex = 0;
    
    for($i=1;$i<$n;$i++){
        $old_inc = $inc;
        $inc = max($inc, $ex + $arr[$i]);    
        $ex = $old_inc;
    }
    echo 'Max Sum Of:'.$inc;
?>