I'm really a green hand and don't know how to test the input of [1],[]. My code is as follows:

```
class Solution
{
public:
void merge(int A[], int m, int B[], int n)
{
int currentindex = m-1;
int index_a=m-n-1;
int index_b=n-1;
while(index_a!=-1 || index_b!=-1)
{
if(index_a!=-1&&index_b!=-1)
{
if(*(A+index_a)>*(B+index_b))
{
*(A+currentindex) = *(A+index_a);
index_a--;
}
else
{
*(A+currentindex) = *(B+index_b);
index_b--;
}
}
else if(index_b!=-1 && !(index_a!=-1))
{
*(A+currentindex) = *(B+index_b);
index_b--;
}
currentindex--;
}
}
};
```