malloc: *** error for object: pointer being freed was not allocated *** set a breakpoint in malloc_error_break to debug
The problem is with this code:
parent.left = &a;parent.right = &b;This is getting pointers to local variables, which will be reinitialized next time around the loop. CharCountNode will eventually try to delete these objects, but they haven't been allocated by new.
You need to make left and right point to objects allocated on the heap, as that is what CharCountNode is expecting. Something like:
parent.left = new CharCountNode(a);parent.right = new CharCountNode(b);