折半查找

public void (int[] array,int key)
{
  int low,high,mid;
  low=0;
  high=array.length-1;
  while(low<=high){
    mid=(low+high)/2;
    if(array[mid]>key){
      high=mid-1;
    }
    else if(array[mid]<key){
      low=mid+1;
    }
    else if(array[mid]==key){
      return mid;
    }
  }
}