折半查找

//折半查找的递归算法
int Search_rec(int r[],int low,int high,int key)
{
    int mid;
    while (low<=high)
    {
        mid = (low+high)/2;
        if (key<r[mid])
            return Search_rec(r,low,mid-1,key);
        else if(key>r[mid])
            return Search_rec(r,mid+1,high,key);
        else
            return mid;
    }
    return -1;
}
//折半查找算法
int Search_rec1(int r[],int low,int high,int key)
{
    int mid;
    while (low<=high)
    {
        mid = (low+high)/2;
        if (key == r[mid])
            return mid;
        else if (key<r[mid])
            high = mid-1;
        else
            low = mid +1;
    }
    return -1;
}