all i need is these two files
Create VectorContainer.hpp
Create SelectionSort.hpp 
Test SelectionSort.hpp using the VectorContainer.hpp class you made
# Strategy Pattern
In this lab you will create a strategy pattern for sorting a collection of expression trees by their `evaluate()` value, which you will pair with different containers to see how strategies can be paired with different clients through an interface to create an easily extendable system. This lab requires a completed composite pattern from the previous lab, so you should begin by copying your or your partner’s code from the previous assignment into your new repo, making sure it compiles correctly, and running your tests to make sure everything is still functioning correctly.

You will start this lab by creating two expression tree containers: one that uses a vector to hold your trees (class `VectorContainer`) and one that uses a standard list (class `ListContainer`). Each of these container classes should be able to hold any amount of different expressions each of which can be of any size. You will implement them both as subclasses of the following `Container` abstract base class, which has been provided to you in container.h. You should create each one independently, creating tests for them using the google test framework before moving on. Each container should be its own commit with a proper commit message. Optionally you can create each one as a branch and merge it in once it has been completed.
class Container {
    protected:
        Sort* sort_function;

    public:
        /* Constructors */
        Container() : sort_function(nullptr) { };
        Container(Sort* function) : sort_function(function) { };

        /* Non Virtual Functions */
        void set_sort_function(Sort* sort_function); // set the type of sorting algorithm

        /* Pure Virtual Functions */
        // push the top pointer of the tree into container
        virtual void add_element(Base* element) = 0;
        // iterate through trees and output the expressions (use stringify())
        virtual void print() = 0;
        // calls on the previously set sorting-algorithm. Checks if sort_function is not
        // null, throw exception if otherwise
        virtual void sort() = 0;

        /* Functions Needed to Sort */
        //switch tree locations
        virtual void swap(int i, int j) = 0;
        // get top ptr of tree at index i
        virtual Base* at(int i) = 0;
        // return container size
        virtual int size() = 0;
};
Notice that our Container abstract base class does not have any actual STL containers because it leaves the implementation details of the container to the subclasses. You **must use the homogeneous interface above for your sort functions, and you are only allowed to manipulate the containers through this interface, not directly**. This will allow you to extend and change the underlying functionality without having to change anything that interfaces with it.

## Sorting Classes
In addition to the containers you will also create two sort functions capable of sorting your containers, one that uses the [selection sort](https://www.mathbits.com/MathBits/CompSci/Arrays/Selection.htm) algorithm and one that uses the [bubble sort](https://www.mathbits.com/MathBits/CompSci/Arrays/Bubble.htm) algorithm (you may adapt this code when writing your sort functions). They should both be implemented as subclasses of the `Sort` base class below which has been provided. You should create each one independently, creating tests for them using the google test framework before moving on. Each sort class should be it’s own commit with its own proper commit message. When creating tests for these sort classes, make sure you test them with each of the containers you developed previously, and with a number of different expression trees.
“`c++
class Sort {
    public:
        /* Constructors */
        Sort();

        /* Pure Virtual Functions */
        virtual void sort(Container* container) = 0;
};

sort.hpp

#ifndef _SORT_HPP_
#define _SORT_HPP_

#include “container.hpp”

class Container;

class Sort {
public:
/* Constructors */
Sort();

/* Pure Virtual Functions */
virtual void sort(Container* container) = 0;
};

#endif //_SORT_HPP_

base.hpp

#ifndef _BASE_HPP_
#define _BASE_HPP_

#include

class Base {
public:
/* Constructors */
Base() { };

/* Pure Virtual Functions */
virtual double evaluate() = 0;
virtual std::string stringify() = 0;
};

#endif //_BASE_HPP_

container.hpp

#ifndef _CONTAINER_HPP_
#define _CONTAINER_HPP_

#include “sort.hpp”
#include “base.hpp”

class Sort;
class Base;

class Container {
protected:
Sort* sort_function;

public:
/* Constructors */
Container() : sort_function(nullptr) { };
Container(Sort* function) : sort_function(function) { };

/* Non Virtual Functions */
void set_sort_function(Sort* sort_function); // set the type of sorting algorithm

/* Pure Virtual Functions */
// push the top pointer of the tree into container
virtual void add_element(Base* element) = 0;
// iterate through trees and output the expressions (use stringify())
virtual void print() = 0;
// calls on the previously set sorting-algorithm. Checks if sort_function is not null, throw exception if otherwise
virtual void sort() = 0;

/* Essentially the only functions needed to sort */
//switch tree locations
virtual void swap(int i, int j) = 0;
// get top ptr of tree at index i
virtual Base* at(int i) = 0;
// return container size
virtual int size() = 0;
};

#endif //_CONTAINER_HPP_

Example

#ifndef _LISTCONTAINER_HPP_
#define _LISTCONTAINER_HPP_

#include “container.hpp”
#include #include
#include
class Sort;

class ListContainer: public Container{
public:

std::list baseList;

//Container() : sort_function(nullptr){};
//Container(Sort* function) : sort_Function(function){};

//void set_sort_funtion(Sort* sort_function){
// this -> sort_function = sort_function;
//}

void add_element(Base* element){
baseList.push_back(element);
}
void print(){
for(std::list::iterator i = baseList.begin(); i != baseList.end(); ++i){
if(i == baseList.begin()){
std::cout <<(*i) -> stringify();
}
else{
std::cout << ", " << (*i) -> stringify();
}
}
std::cout << std::endl; } void sort(){ try{ if(sort_function != nullptr){ sort_function -> sort(this);
}
else{
throw std::logic_error(“invalid sort_function”);
}
}
catch(std::exception &exp){
std::cout << "ERROR : " << exp.what() << "n"; } } //sorting functions void swap(int i, int j){ std::list::iterator first = baseList.begin();
for(int f = 0; f < i; f++){ first++; } Base* temp = *first; std::list::iterator second = baseList.begin();
for(int s = 0; s < j; s++){ second++; } *first = *second; *second = temp; } Base* at(int i){ std::list::iterator x = baseList.begin();
for(int a = 0; a < i; a++){ x++; } return *x; } int size(){ return baseList.size(); } }; #endif //_LISTCONTAINER_HPP_ bubblesort.hpp #ifndef __BUBBLESORT_HPP__ #define __BUBBLESORT_HPP__ #include "sort.hpp" #include "container.hpp" class BubbleSort: public Sort{ public: void sort(Container* container){ memContainer = container;                int flag = 1;                int numLength = memContainer->size();
               for(int i = 1; (i <= numLength) && (flag == 1); i++){                        flag = 0; for(int j = 0; j < (numLength - 1); j++){ if(memContainer->at(j+1)->evaluate() < memContainer->at(j)->evaluate()){
memContainer->swap(j+1, j);
flag = 1;
}
}
}
}
};
#endif // __BUBBLESORT_HPP__