C++ :: Checking For Deallocated Memory?

How would I go about checking for deallocated memory?

For example, let's take this into consideration:

// Unsigned 32-bit / 64-bit integer: uint32, uint64
uint32* Pointer = new uint32[ Size ];
uint64 MemAddr = ( uint64 ) Pointer;
delete[] Pointer;

The above code would proceed to create a new array, store it in a pointer and retrieve the memory address of the array before finally deleting the array.

So let's assume we re-build the pointer and try to access the now deallocated array:

Pointer = ( uint32* ) MemAddr;
Pointer[ 0 ] = 0;

Based on the above snippets of code, how would I check "Pointer" after rebuilding the memory to check if the rebuilt memory has actually been deallocated. Without a check we'd get an exception error.

A bit of detail on why I am trying this:

Before thinking up how to do this, I was storing the addresses in a list and check the list for the addresses to see if they existed or not. However this requires an O(n) search, which isn't exactly what I am wanting. So instead if I used a check for deallocation method, I can go for an O(1) time check and reduce the total time it would take to check for memory allocation/deallocation.