/** * 鏈表結構 */class Child{  public $no;  public $next=null;  public function __construct($no=null){    $this->no = $no;  }}/** * 鏈表操作 */class CycleLink{  private $nodeNum = 0;  /**   * 添加節點   */  public function addNode($head,$node)  {    $currentNode = $head;    while ($currentNode->next!=null && $currentNode->next!=$head) {      $currentNode = $currentNode->next;    }    $currentNode->next = $node;    $currentNode->next->next = $head;    $this->nodeNum++;  }  /**   * 刪除節點   */  public function delNode($head,$no)  {    $currentNode = $head;    while ($currentNode->next!=$head) {      if($currentNode->next->no==$no){        $currentNode->next = $currentNode->next->next;        $this->nodeNum--;        break;      }      $currentNode = $currentNode->next;    }  }  /**   * 獲取節點數量   */  public function getNodeNum(){    return $this->nodeNum;  }  /**   * 查找節點   */  public function findNode($head,$no){    $node = null;    $currentNode = $head;    while ($currentNode->next!=$head) {      if($currentNode->next->no==$no){        $node = $currentNode->next;        break;      }      $currentNode = $currentNode->next;    }    return $node;  }  public function getNextNode($head,$node){    if($node->next==$head){      return $node->next->next;    }    return $node->next;  }  /**   * 顯示節點   */  public function showNode($head)  {    echo "<br/><br/>";    $currentNode = $head;    while ($currentNode->next!=$head){      $currentNode = $currentNode->next;      echo '第 '.$currentNode->no.' 名小孩<br/>';    }  }}/*//創建一個head頭,該head 只是一個頭，不放入數據$head     = new Child();$childList   = new CycleLink();$child_1   = new Child(1);$child_2   = new Child(2);$child_3   = new Child(3);$child_4   = new Child(4);$childList->addNode($head,$child_1);$childList->addNode($head,$child_2);$childList->addNode($head,$child_3);$childList->addNode($head,$child_4);$childList->showNode($head);echo "<pre>";var_dump($head);$findNode = $childList->findNode($head,3);echo "<pre>";var_dump($findNode);$childList->delNode($head,2);$childList->showNode($head);echo $childList->getNodeNum();exit();*//** * 約瑟夫問題 * 設編號為1，2，...n的n個人圍坐一圈，約定編號為k（1<=k<=n）的人從1開始報數，數到m的那個人出列， * 它的下一位又從1開始報數，數到m的那個人又出列，依次類推，直到所有人出列為止，由此產生一個出隊編號的序列。 * 并求出最后出列的人是哪個？ */class Josephu{  private $head;  private $childList;  private $k;  private $m;  private $n;  public function __construct($n,$k,$m){    $this->k = $k;    $this->m = $m;    $this->n = $n;    $this->createList($n);  // 創建小孩    echo "<br/><br/>當前有 {$n} 個小孩，從第 {$k} 個小孩開始報數，數到 {$m} 退出<br/><br/>";  }  // 數數  public function exec(){    $currentNode = $this->childList->findNode($this->head,$this->k);  // 獲取第一個開始報數的人    $_num = 0;  // 當前數到的值    $surplus_num = $this->n;    // 開始報數    while ($surplus_num>1) {  // 只要人數大于1，就繼續報數      // 當前報數值      $_num++;      $nextNode = $this->childList->getNextNode($this->head,$currentNode);      // 數至第m個數，然后將其移除。報數恢復到0，重新循環。      if( $_num==$this->m ){        $_num = 0;        $surplus_num--;        // 當前小孩退出        $this->childList->delNode($this->head,$currentNode->no);        echo '<br/>退出小孩編號：' . $currentNode->no;      }      // 移動到下一個小孩      $currentNode = $nextNode;    }    echo '<br/>最后一個小孩編號：' . $currentNode->no;  }  // 創建小孩  private function createList($n){    $this->childList = new CycleLink();    $this->head = new Child();    for ($i=1;$i<=$n;$i++){      $node = new Child($i);      $this->childList->addNode($this->head,$node);    }    $this->childList->showNode($this->head);  }}$josephu = new Josephu(4, 1, 2);$josephu->exec();