Issue with swapping addresses - c++

Question

I am doing an assignment in which i must write a function that does the following - "You will allocate an array the size of the number of vacancies and load the dynamic array with the pointers to all of the current vacancies. Build the array using the last vacancy first. in this same function, you will move all of the transfers to the available rooms (and mark them as OCCUPIED) using the dynamic array of pointers. You must do this by performing a swap of the transfer addresses with the vacant ones. Start from the back of the array of pointers and continue to the front for these operations until all transfers are done. DO NOT REPROCESS the array of pointers." This is what i wrote in an attempt to do this -
char** tranfers(char hospitalFloors[FLOOR_ARRAY_SIZE][ROOM_ARRAY_SIZE], int &num)
{
int x = 0;
char *temp;
for (int i = 0; i < FLOOR_ARRAY_SIZE; i++)
{
for (int k = 0; k < ROOM_ARRAY_SIZE; k++)
{
if(hospitalFloors[i][k] == 'V')
{
num++;
}
}
}
char **arr = new char*[num];
for (int i = (FLOOR_ARRAY_SIZE - 1); i >= 0; i--)
{
for (int k = (ROOM_ARRAY_SIZE - 1); k >= 0; k--)
{
if (hospitalFloors[i][k] == 'V')
{
arr[x] = &hospitalFloors[i][k];
x++;
}
}
}
for (int i = 0; i < FLOOR_ARRAY_SIZE; i++)
{
for (int k = 0; k < ROOM_ARRAY_SIZE; k++)
{
if (hospitalFloors[i][k] == 'T')
{
x--;
temp = arr[x];
arr[x] = &hospitalFloors[i][k]
&hospitalFloors[i][k] = temp;
}
}
}
return arr;
}
i have no doubt in my mind that there is a problem with trying to set &hospitalFloors[i][k] to a pointer, but no matter what i try differently i cant seem to come up with a solution.
my question is, given what the assignment is asking, how would i swap the address of the room with a transfer to a room with a patient, making sure that the array of pointers keeps its order, but without reprocessing it?
Any help is greatly appreciated.

Answer 1

The wording of the question is quite a bit vague. It looks like what you need to do is move any room marked as a transfer ('T') to a vacant room ('V') and mark it as occupied (assuming 'O') and mark the room transferred from as vacant.
So all you need to do is take the appropriate steps in your last if block.
*arr[x] = 'O'; // set vacant room as occupied.
hospitalFloors[i][j] = 'V'; // set transfer room as vacant
arr[x] = &hospitalFloors[i][j]; // make the vacancy element point at the now vacant room
Of course keeping x--

Answer 2

You do need to work on the pointed-to data, of type char. While the assignment says "swap", it also says to mark the moved transferee rooms occupied, which you could do directly:
*arr[x] = 'O';
hospitalFloors[i][k] = 'V';
To do it literally using a "swap" first:
char temp = *arr[x]; // was vacant
*arr[x] = hospitalFloors[i][k]; // assign transfer
hostpitalFloors[i][k] = temp; // make vacant
*arr[x] = 'O'; // make occupied
The array does say...
You must do this by performing a swap of the transfer addresses with the vacant ones.
It's unclear if addresses above alludes to the [floor][room] aspect, or the char* aspect. There's ostensibly no point in modifying the pointer addresses in arr though, so I'm assuming the former.
You are asked to do this in reverse order of the array though, but you're currently looping over the floors and rooms again. I'm sure you can fix that yourself.