3n+1 Php Implementation

3n.php

<?php
ini_set('xdebug.max_nesting_level', 10000000);
function isOdd($n)
{
    return ($n & 1);
}

function getStepCount($number, &$cache)
{
    $count = 1;

    $n = $number;

    while ( $n > 1 ) {
        if ( isset($cache[$n]) ) {
            $count = $count + $cache[$n] - 1;
            break;
        }

        $count++;

        if ( isOdd($n) ) {
            $n = 3 * $n + 1;
        } else {
            $n = $n / 2;
        }
    }

    $cache[$number] = $count;

    return $count;
}


function evaluateAlgorithm($n, &$cache)
{
    if ( isset($cache[$n]) ) {
        return $cache[$n];
    }

    if ( $n <= 1 ) {
        $count = 0;
    } elseif ( isOdd($n) ) {
        $count = evaluateAlgorithm(3 * $n + 1, $cache);
    } else {
        $count = evaluateAlgorithm($n / 2, $cache);
    }

    return $cache[$n] = $count + 1;
}

function getValidInput($argc, $argv)
{
    $n = array();
    switch ( $argc ):
        case 3 :
            $n = array($argv[1], $argv[2]);
            break;
        case 2 :
            $n = explode(",", $argv[1]);
            break;
        default :
    endswitch;

    if ( count($n) == 2 && $n[0] <= $n[1] && $n[0] > 0 && $n[1] < 1000000 ) {
        return $n;
    }

    die("Invalid Input" . PHP_EOL);
}

function getMaximumStep($i, $j, &$cache, $stepCounter = 'getStepCount')
{
    if ( $i > $j ) {
        return "Wrong Input";
    }

    $data = array(
        'max_step'   => 0,
        'max_step_n' => FALSE
    );

    for ($n = $i; $n <= $j; $n++) {
        $current_steps = $stepCounter($n, $cache);

        if ( $current_steps > $data['max_step'] ) {
            $data['max_step']   = $current_steps;
            $data['max_step_n'] = $n;
        }
    }

    return "Maximum Step (" . $data['max_step'] . ") Needed for number : " . $data['max_step_n'];
}

$cache  = array();
$cache1 = array();

$n = getValidInput($argc, $argv);

echo PHP_EOL . "======= Using Loop ========" . PHP_EOL;
$eStart = microtime(TRUE);
echo getMaximumStep($n[0], $n[1], $cache) . PHP_EOL;
$eEnd = microtime(TRUE);
echo 'Execution time: ' . ($eEnd - $eStart) * 1000 . ' ms' . PHP_EOL;


echo PHP_EOL . "======= Using Recursion ========" . PHP_EOL;
$eStart = microtime(TRUE);
echo getMaximumStep($n[0], $n[1], $cache1, 'evaluateAlgorithm') . PHP_EOL;
$eEnd = microtime(TRUE);
echo 'Execution time: ' . ($eEnd - $eStart) * 1000 . ' ms' . PHP_EOL;

echo PHP_EOL . "======= Using Recursion Again ========" . PHP_EOL;
$eStart = microtime(TRUE);
echo getMaximumStep($n[0], $n[1], $cache1, 'evaluateAlgorithm') . PHP_EOL;
$eEnd = microtime(TRUE);
echo 'Execution time: ' . ($eEnd - $eStart) * 1000 . ' ms' . PHP_EOL;