public class BinarySearch {
 public static void main(String[] args){
 int searchArr[] = new int[1000000];
 for(int i=0;i<1000000;i++){
  searchArr[i]=i;
 }
   System.out.println(binSearch(searchArr,0,searchArr.length-1,99));
    System.out.println(binSearch(searchArr,99));
  }
//递归二分查找
  public static int binSearch(int arr[], int start,int end,int sear){
    int mid = (end-start)/2 + start;
    if(sear==arr[mid]){
      return mid;
    }
    if(start>=end){
      return -1;
    }else if(sear < arr[mid]){
      return binSearch(arr,0,mid-1,sear);
    }else if(sear >arr[mid]){
      return binSearch(arr,mid+1,end,sear);
    }
    return -1;
  }
//循环二分查找
  public static int binSearch(int arr[],int key){
    int mid = arr.length/2;
    int start = 0;
    int end = arr.length-1;
    while(start<=end){
      mid = (end-start)/2+start;
      if(key ==arr[mid]){
        return mid;
      }else if(key <= arr[mid]){
        end = mid-1;
      }else if(key >=arr[mid]){
        start = mid+1;
      }
    }
    return -1;
  }