二分查找

int binarysearch(int arry[], int n, int goal)
{
    int low = -1;
    int high = n;
    while(low + 1 < high)
    {
        int mid = (low + high) >> 1;
        if(arry[mid] < goal)
        {
            low = mid;
        }
        else
        {
            high = mid;
        }
    }

    int value = high;
    if(high >= n || arry[high] != goal)
        value = -1;
    cout<<"low is "<<low<<",high is "<<high<<",value is "<<value<<endl;
    return 0;
}