take-sample-test-binary_gap.php

<?php

function solution($N) {
    //print "N: $N\n";
    // write your code in PHP5.5
    $bin = base_convert($N, 10, 2);
    $sbin = trim((string) $bin);
    //print "sbin: $sbin\n";

    $any_zero = strpos($sbin, '0');
    //print "any zero: ". var_dump($any_zero, true). "\n";

    // The function should return 0 if N doesn't contain a binary gap
    if ($any_zero === false) return 0;

    $array = explode('1', trim($sbin));
    usort($array, "cmp");
    //print_r($array);

    foreach($array as $key => $value) {
        $find = "1{$value}1";
        //print "value: $value\n";
        //print "find: $find\n";
        if ($value == '') return 0;
        $strpos = strpos($sbin, $find);
        //print "sp: " . $strpos . "\n";
        if ($strpos !== false) return strlen($value);
    }

    return 0;
}

function cmp($a, $b) {
    $la = strlen($a);
    $lb = strlen($b);

    if ($la == $lb) return 0;
    return ($la > $lb) ? -1 : 1;
}