二分查找 模板（升序数组）

int binSearch(const int arr[],int low,int high,int key)
{
   if(low>high)
        return -1;
   int mid=low+(high-low)/2;
   if(arr[mid] == key)
        return mid;
   return (arr[mid] > key ? binSearch(arr,low,mid-1,key) : binSearch(arr,mid+1,high,key));
}