Data structure Lookup (PHP code implementation)

/** * search_seq ($arr, $elem): Order lookup  * search_seq2 ($arr, $elem): Sequential lookup (optimization)  * search_ Bin ($arr, $elem): Binary find  * searchbst ($elem): two forks search  */class search{    public   $arr;     function __construct ($arr)     {          $this->arr =  $arr;    }     /**     *  Sequential Find      *  @param   $arr    in $arr Array Find      *  @param   $elem   Find if there is an element $elem in the array, the position returned in the array, or 0      */    public static function search_seq ($arr, $elem) {        for ($i =0; $i <count ($arr); $i +)  {             if ($arr [$i]== $elem) {                 return  $i;             }        }         return 0;    }    //This algorithm is an optimization of the above algorithm     &NBSP;PUBLIC&NBSP;STATIC&NBSP;FUNCTION&NBSP;SEARCH_SEQ2 ($arr, $elem) {          $i =0;        while ($arr [$i]!= $elem) {              $i ++;        }         return  $i;     }    /**      *  Binary lookup (also called binary lookup), provided the array must be ordered-from small to large      * @ param  $arr    Find in the $arr array      *  @param   $elem   Find out if there are elements in an array Elem, with the position returned in the array, or 0&NBsp;    */    public static function search_bin ($arr, $ Elem) {         $low =0;        $ High=count ($arr);         while ($low <= $high) {              $mid =round (($low + $high)/2);//              $mid = $low + ($low + $high) * ($elem-$arr [$low])/($arr [$high]-$arr [$ Low]);  //If you change the value of $mid to this sentence, it becomes an interpolation lookup. This finding algorithm is more efficient than binary when the data size distribution is more uniform.             if ($elem < $arr [$mid]) {                  $high = $mid -1;             }else if ($elem > $arr [$mid]) {                  $low = $mid +1;            }else{                 return $ mid;            }         }        return 0;    }     /**     *  Two fork sort tree      * @ param  $elem      *  @return  int     */     public function searchbst ($elem) {       return   $this->find ($this->arr[0], $elem, 0);    }    private  Function find ($root, $elem, $i) {        if ($i >count ($this ARR)  | |  ! $root) {            return  ' Error ';         }        if ($elem = = $root) {             return  $i;         }        if ($elem < $root  &&  $i +1<count ($this->arr)) {            return    $this->find ($this->arr[$i *2+1], $elem, $i *2+1);         }else if ($elem > $root  &&  $i *2+2<count ($this->arr) {             return   $this->find ($this->arr[$i *2+2],$ Elem, $i *2+2);        }         Return 0;   &nBSP;}} 

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Data structure Lookup (PHP code implementation)