Part I: Class Design

Re$-$write the Formula class in C$++,$ the type definition of Formula is the same as in P$1$

Files must be named formula.h and formula.cpp

Write a second class, Plan, that represents a sequence of Formulas to be applied in order.

Files must be named plan.h and plan.cpp

A Plan should allow the client to:

$$ Add a new Formula to the end of the sequence.

$$ Remove the last Formula from the end of the sequence.

$$ Replace a Formula anywhere in the sequence.

Use dependency injection to provide an initial sequence of Formulas. The Plan class must

properly implement C$++$ copy and move semantics. The Plan copy constructor and copy

assignment operator should support deep copying of all internal Formulas so that no

unintended aliasing occurs: e$.$g$.$ after copying Plan object x$,$ any actions on object x$,$ such

as leveling up a Formula, should not affect any copy of x$.$

The Plan class must implement a destructor to appropriately dispose of owned resources.

Each Plan object encapsulates some number of distinct Formula objects, with addition, removal

and replacement of Formula objects supported as specified above $$ thus the cardinality of Formula

subobjects varies across Plan objects. You decide what, if any, additional public functionality

should be supported., remembering that exposure should be minimized and queries should not

affect state.