来自新浪微博的面试题

php内核解析-引用

第一题应该考的是strtotime

echo date('Y-m-d H:i:s',strtotime('-1 day'));

:thumbsup:

第二题真不错。没想到。。。反正我肯定想不到这个结果。。。

看样子是进不去新浪了 ?

猴子的问题似乎不需要递归? :grinning:

function monkey($monkey, $x) {
    $arr = range(1, $monkey);
    $i   = 0;
    while (count($arr) > 1) {
        if (($i+1) % $x !== 0) {
            array_push($arr, $arr[$i]);
        }
        unset($arr[$i]);
        $i++;
    }
    return implode('', $arr);
}

echo 'The winner is ' . monkey(5, 5);

@Kerwin 递归算的次数少了点咯

新浪的题挺简单的，猴子选大王这题好多公司用啊

`$arr=
[
'赵','钱','孙','李',
'周','吴','郑','王',
'冯','陈','褚','魏',
'蒋','沈','韩','杨'
];

function countM($arr,$step)
{
$i=1;

while (count($arr)>1)
{
    if ($i==$step)
    {
        array_shift($arr);
        $i=0;
    }else
    {
        array_push($arr,array_shift($arr));
    }

    $i++;
}

echo array_shift($arr);

}`

猴子的问题, 代码如下：

function king ($n, $m){
    $s = 0;
    for($i=1;$i<=$n;$i++) {
        $s = ($s+$m)%$i;
    }
    return $s+1;
}

echo king(5,2);     // 3

猴子问题：
写一个环形队列，问题就迎刃而解了。

class RingQueue
{
    protected $items = [];

    public function __construct($items = [])
    {
        $this->items = array_values($items);
    }

    public function current()
    {
        return current($this->items);
    }

    public function key()
    {
        return key($this->items);
    }

    public function next()
    {
        $next = next($this->items);
        if ($next === false) {
            reset($this->items);
            return current($this->items);
        }

        return $next;
    }

    public function nextByStep($step)
    {
        $i = 0;
        for ($i; $i < $step; $i++) {
            $this->next();
        }
        return current($this->items);
    }

    public function count()
    {
        return count($this->items);
    }

    public function add($item)
    {
        $this->items[] = $itme;
        return $this;
    }

    public function remove($index)
    {
        unset($this->items[$index]);
        if (current($this->items) === false) {
            reset($this->items);
        }
        return $this;
    }

    public function print()
    {
        return implode(',', $this->items);
    }
}

function game(ringQueue $monkeys, $round)
{
    $count = $monkeys->count();

    if ($count === 1) {
        echo 'Game Over.' . PHP_EOL;
        echo 'Winner: ' . $monkeys->current() . PHP_EOL;
        return;
    }

    echo 'Round: ' . $round . PHP_EOL;
    echo 'Monkeys: ' . $monkeys->print() . PHP_EOL;
    echo 'Current Monkey: ' . $monkeys->current() . PHP_EOL;

    $step = rand(0, $count - 1);
    echo 'Step: ' . ($step + 1) . PHP_EOL;

    $outMonkey = $monkeys->nextByStep($step);

    $monkeys->remove($monkeys->key());

    echo 'Out Monkey: ' . $outMonkey . PHP_EOL;    

    echo '--------------------------' . PHP_EOL;

    game($monkeys, $round + 1);
}

$ringQueue = new ringQueue(['A', 'B', 'C', 'D']);
game($ringQueue, 1);

结果：

Round: 1
Monkeys: A,B,C,D
Current Monkey: A
Step: 2
Out Monkey: B
--------------------------
Round: 2
Monkeys: A,C,D
Current Monkey: C
Step: 1
Out Monkey: C
--------------------------
Round: 3
Monkeys: A,D
Current Monkey: D
Step: 2
Out Monkey: A
--------------------------
Game Over.
Winner: D

@Kerwin Note: 如果用 array_push() 来给数组增加一个单元，还不如用 $array[] = ，因为这样没有调用函数的额外负担。

class Node
{
    public $next;
    public $value;

    public function __construct($value)
    {
        $this->value = $value;
    }

    public function setNext($node)
    {
        $this->next = $node;
        return $this->next;
    }
}

function monkey($step, $node)
{
    if ($node->value == $node->next->value) return $node;
    $preNode = $node;
    for ($i = 0; $i < $step; $i++) {
        $preNode = $node;
        $node = $node->next;
    }
    $preNode->next = $node->next;
    return monkey($step, $preNode);
}

$node = new Node(1);
$next = $node->setNext(new Node(2));
$next = $next->setNext(new Node(3));
$next = $next->setNext(new Node(4));
$next = $next->setNext(new Node(5));
$next = $next->setNext(new Node(6));
$next = $next->setNext($node);

var_dump(monkey(2, $node));

欢迎指正