每日一算法【one】

//有一个数组  {1,2,3,4,5,6,7,8,9,12,13,45,67,89,99,101,111,123,134,565,677} 查找数组中是否有指定的某一个数.

 /**
   *----------------------------------------
   * Time:2016-06-21 | 二分查找
   *---------------------------------------
   */
 function binarySearch(&$arr,$findVal,$leftIndex,$rightIndex){
   if($rightIndex < $leftIndex){
     echo "哇哇哇,找不到o(︶︿︶)o 唉";
     return;
   }
   // @ 取中间的key
   $middleIndex=round(($rightIndex+$leftIndex)/2);
   if($findVal > $arr[$middleIndex]){
     binarySearch($arr,$findVal,$middleIndex+1,$rightIndex);
   }else if($findVal < $arr[$middleIndex]){
     binarySearch($arr,$findVal,$leftIndex,$middleIndex-1);
   }else{
     echo "哇哇哇找到你了o(∩_∩)o 哈哈。下标是$middleIndex";
   }
 }
     $arr=array(1,2,3,4,5,6,7,8,9,12,13,45,67,89,99,101,111,123,134,565,677);
     print_r(binarySearch($arr,89,0,count($arr)-1));