solution.php

class Solution {

    private $arr = [];
    /**
     * @param Integer[] $arr
     * @return String
     */
    function largestTimeFromDigits($arr) {
        $this->arr = $arr;
        $two = $this->getOneOf([2]);
        if ($two !== false) {
            $b = $this->getOneOf([3,2,1,0]);
            if($b !== false) {
                $c = $this->getOneOf([5,4,3,2,1,0]);
                if($c !== false) {
                    $d = $this->getBest();
                    return "$two$b:$c$d";
                } else {
                    $this->putBack($b);
                    $this->putBack($two);
                }
            } else {
                $this->putBack($two);  
            } 
        }
        $one = $this->getOneOf([1]);
        if($one !== false) {
            $b = $this->getBest();
            $c = $this->getOneOf([5,4,3,2,1,0]);
            if($c !== false) {
                $d = $this->getBest();
                return "$one$b:$c$d";
            } else {
                $this->putBack($b);
                $this->putBack($one);
            }
        }
        
        $zero = $this->getOneOf([0]);
        if($zero !== false) {
            $b = $this->getBest();
            $c = $this->getOneOf([5,4,3,2,1,0]);
            if($c !== false) {
                $d = $this->getBest();
                return "$zero$b:$c$d";
            } else {
                $this->putBack($zero);
                $this->putBack($b);
            }
        }
        return "";
    }
    
    
    function putBack($num) {
        $this->arr[] = $num;
        $this->arr = array_values($this->arr);
    }
    
    function getNum ($num) {
        for($i = 0;$i<count($this->arr);$i++) {
            if($this->arr[$i] == $num) {
                unset($this->arr[$i]);
                $this->arr = array_values($this->arr);
                return $num;
            }
        }
        return false;
    }
    
    function getOneOf($a) {
        foreach($a as $i=>$v) {
            $val = $this->getNum($v);
            if($val !== false) {
                // unset($this->arr[$i]);
                $this->arr = array_values($this->arr);
                return $val;
            }
        }
        return false;
    }
    
    function getBest()
    {
        $max = PHP_INT_MIN;
        $maxIndex = false;
        // var_dump($this->arr);
        foreach($this->arr as $i => $v) {
            if($v > $max) {
                $max = $v;
                $maxIndex = $i;
            }
        }
        unset($this->arr[$maxIndex]);
        $this->arr = array_values($this->arr);
        return $max;
    }
}