Please help with this C++ //Implement functions of class linked_list and class bag //All member functions listed in the two class needs implementation //note that some are already done //Need to implement the overloaded operator<< for all classes, including vector //See the sample output for formats when implementing operator<< for all classes #include  #include  #include  #include  using namespace std; template  class ThreeD { public: T ht; T wid; T dep; ThreeD() { ht = wid = dep = 0; } ThreeD(T i) { ht = wid = dep = i; } ThreeD(T a, T b, T c) { ht = a; wid = b; dep = c; } bool operator==(ThreeD &t) { return (ht == t.ht && wid = t.wid && dep == t.dep); } bool operator!=(ThreeD &t) { return (ht != t.ht || wid != t.wid || dep != t.dep); } template  friend ostream & operator<<(ostream &s, const ThreeD &t); }; template  class node { public: T value; node * next; node * previous; node() { next = nullptr; previous = nullptr; } node(T v) { value = v; next = nullptr; previous = nullptr; } }; template  class linked_list { public: int num_nodes; node * head;10/15 node * tail; linked_list() { num_nodes = 0; head = tail = nullptr; } linked_list(const initializer_list &V); void push_front(T t); void push_back(T t); bool operator==(linked_list &L); linked_list(const linked_list &L); ~linked_list(); void operator=(const linked_list &L); template  friend ostream & operator<<(ostream &s, const linked_list &L); }; template  void linked_list::push_front(T t) { node * p = new node(t); if (head == nullptr) { head = tail = p; num_nodes++; } else { p->next = head; head->previous = p; head = p; num_nodes++; } } template  void linked_list::push_back(T t) { node * p = new node(t); if (head == nullptr) { head = tail = p; num_nodes++; } else { p->previous = tail; tail->next = p; tail = p; num_nodes++; } } template  class item { public: X value; item *next; item *previous; item(X v) { value = v; next = nullptr; previous = nullptr; } bool operator==(item I) { return value == I.value; } template  friend ostream & operator<<(ostream &s, const item &I); }; template  class bag { public: item *last; item *first; int num_items; int size() { return num_items; } //void show_bag();//Print all items in the bag bag() { last = nullptr; first = nullptr; num_items = 0; } //default constructor for bag class bag(const initializer_list &V); ~bag();//destructor bag(const bag & B);//copy constructor void operator=(const bag & B); //operator= ; left value reference void push_back(X v); //insert an item with value v to the back of the bag void push_front(X v); //insert an item with value v to the front of the bag void pop_back(); //delete the last item in the bag void pop_front(); //delete the first item in the bag X &operator[](int i); //Access bag item with index. X front() { //it returns the value of the first item in the bag. //if (num_items == 0) cout << "Error! The bag is empty! "; //else return first->value; } X back() { //it returns the value of the last item in the bag /* if (num_items == 0) { cout << "Error! The bag is empty! "; } else */ return last->value; } void clear(); //Delete all items in the bag item * find(X I); void erase(int index); void erase(item * p); template  friend ostream & operator<<(ostream &s, const bag &B); }; template void bag::push_front(X v) { item *p; p = new item(v); if (num_items == 0) { first = last = p; } else { first->previous = p; p->next = first; first = p; } num_items++; } template void bag::push_back(X v) { item *p = new item < X >(v); if (num_items == 0) { first = last = p; } else { p->previous = last; last->next = p; last = p; } num_items++; } template void bag::pop_back() { item *p; if (num_items == 0) cout << "Error! The bag is empty! "; else { p = last->previous; delete last; last = p; num_items--; if (num_items == 0) first = nullptr; else last->next = nullptr; } } template void bag::pop_front() { item *p; if (num_items == 0) { return; } else { p = first->next; delete first; first = p; num_items--; if (num_items == 0) last = nullptr; else first->previous = nullptr; } } int main() { bag bag_d; bag_d.push_back(5.5); bag_d.push_back(6.6); bag_d.push_front(4.4); bag_d.push_front(3.3); bag_d.pop_front(); bag_d.pop_back(); cout << bag_d << endl;; bag bag_i; bag_i.push_back(5); bag_i.push_back(6); bag_i.push_front(4); bag_i.push_front(3); bag_i.pop_front(); bag_i.pop_back(); cout << bag_i << endl; ThreeD td3(3), td4(4), td5(5), td6(6), td7(100, 200, 300); bag> bag_3D; bag_3D.push_back(td5); bag_3D.push_back(td6); bag_3D.push_front(td4); bag_3D.push_front(td3); bag_3D.pop_front(); bag_3D.pop_back(); cout << bag_3D << endl;; cout << bag_3D.front() << bag_3D.back(); cout << bag_3D[0] << " " << bag_3D[1] << endl; bag_3D[1] = td7; cout << bag_3D[0] << " " << bag_3D[1] << endl; bag_3D.clear(); cout << bag_3D << endl;; cout << bag_3D.size() << endl; linked_listls_1; ls_1.push_front("David"); ls_1.push_front("John"); ls_1.push_front("Pat"); ls_1.push_front("Ben"); ls_1.push_front("Jeff"); cout << ls_1 << endl; linked_listls_2; ls_2.push_front("Wendy"); ls_2.push_front("Mary"); ls_2.push_front("Nancy"); ls_2.push_front("Jennifer"); cout << ls_2 << endl; bag> bag_string; bag_string.push_back(ls_1); bag_string.push_back(ls_2); cout << bag_string << endl; cout << bag_string[1] << endl; ThreeD t10(3.2, 7.4, 8.9), t11(5.6, 7.7, 2.987), t12(4.6, 7.5, 3.1416), t13(55.6, 66.8, 333.45); linked_list> LTD1; LTD1.push_front(t10); LTD1.push_front(t11); linked_list> LTD2; LTD2.push_front(t13); LTD2.push_front(t12); LTD2.push_front(t10); LTD2.push_front(t11); bag > > BLTD; BLTD.push_back(LTD1); BLTD.push_back(LTD2); cout << BLTD << endl; item>> * p2; p2 = BLTD.find(LTD1); BLTD.erase(p2); cout << BLTD << endl; BLTD.push_back(LTD1); cout << BLTD << endl; BLTD.erase(0); cout << BLTD << endl; vector> V1 = { { 1,2,3 },{ 4,5,6 },{ 7,8,9 } }; cout << V1 << endl; //bag> V2 = { {1,2,3}, {4,5,6}, {7,8,9} }; vector>> V2 = { { { 1,2,3 },{ 4,5,6 },{ 7,8,9 } },{ { 20,30,40 },{ 11,22, 33 } } }; cout << V2 << endl; vector>> V3 = { { { 1, 2, 3 },{ 4, 5 } },{ { 6,7 },{ 8, 9, 10 } } }; cout << V3 << endl; bag B10 = { 1,2,3,4,5 }; bag B11 = B10, B12; B12 = B10; cout << B10 << endl; B10.first->value = 1000; cout << B10 << endl; cout << B11 << endl; cout << B12 << endl; bag>>> B13 = { { { { 1,2,3 },{ 4,5,6 } },{ { 7,8,9 },{ 10,11,12 },{ 13,14,15 } } },{ { { 16,17,18 },{ 19,20,21 },{ 22,23,24 } },{ { 25,26,27 },{ 28,29,30 } },{ { 31,32,33 },{ 34,35,36 },{ 37,38,39 },{ 40,41,42 } } } }; cout << B13 << endl; bag>>> B14 = { { { { 1,2,3 },{ 4,5,6 } },{ { 7,8,9 },{ 10,11,12 },{ 13,14,15 } } },{ { { 16,17,18 },{ 19,20,21 },{ 22,23,24 } },{ { 25,26,27 },{ 28,29,30 } },{ { 31,32,33 },{ 34,35,36 },{ 37,38,39 },{ 40,41,42 } } } }; cout << B14 << endl; bag> * p10 = new bag>({ { 1,2,3,4 },{ 5,6,7 } }); cout << *p10 << endl; delete p10; bag>>> B15 = { { { { 1,2,3 },{ 4,5,6 } },{ { 7,8,9 },{ 10,11,12 },{ 13,14,15 } } },{ { { 16,17,18 },{ 19,20,21 },{ 22,23,24 } },{ { 25,26,27 },{ 28,29,30 } },{ { 31,32,33 },{ 34,35,36 },{ 37,38,39 },{ 40,41,42 } } } }; cout << B15 << endl; B15.erase(1); cout << B15 << endl; getchar(); getchar(); return 0; } //The following is a screenshot of a sample output /* 4.4 5.5 4 5 ( 4, 4, 4 ) ( 5, 5, 5 ) ( 4, 4, 4 )( 5, 5, 5 )( 4, 4, 4 ) ( 5, 5, 5 ) ( 4, 4, 4 ) ( 100, 200, 300 ) 0 Jeff Ben Pat John David Jennifer Nancy Mary Wendy Jeff Ben Pat John David Jennifer Nancy Mary Wendy Jennifer Nancy Mary Wendy ( 5.6, 7.7, 2.987 ) ( 3.2, 7.4, 8.9 ) ( 5.6, 7.7, 2.987 ) ( 3.2, 7.4, 8.9 ) ( 4.6, 7.5, 3.1416 ) ( 55.6, 66.8, 333.45 ) ( 5.6, 7.7, 2.987 ) ( 3.2, 7.4, 8.9 ) ( 4.6, 7.5, 3.1416 ) ( 55.6, 66.8, 333.45 ) ( 5.6, 7.7, 2.987 ) ( 3.2, 7.4, 8.9 ) ( 4.6, 7.5, 3.1416 ) ( 55.6, 66.8, 333.45 ) ( 5.6, 7.7, 2.987 ) ( 3.2, 7.4, 8.9 ) ( 5.6, 7.7, 2.987 ) ( 3.2, 7.4, 8.9 ) [( 1, 2, 3 ), ( 4, 5, 6 ), ( 7, 8, 9 )] [( 1, 2, 3 ) ( 4, 5, 6 ) ( 7, 8, 9 ) , ( 20, 30, 40 ) ( 11, 22, 33 ) ] [1 2 3 4 5 , 6 7 8 9 10 ] 1 2 3 4 5 1000 2 3 4 5 1 2 3 4 5 1 2 3 4 5 [( 1, 2, 3 ) ( 4, 5, 6 ) , ( 7, 8, 9 ) ( 10, 11, 12 ) ( 13, 14, 15 ) ] [( 16, 17, 18 ) ( 19, 20, 21 ) ( 22, 23, 24 ) , ( 25, 26, 27 ) ( 28, 29, 30 ) , ( 31, 32, 33 ) ( 34, 35, 36 ) ( 37, 38, 39 ) ( 40, 41, 42 ) ] ( 1, 2, 3 ) ( 4, 5, 6 ) ( 7, 8, 9 ) ( 10, 11, 12 ) ( 13, 14, 15 ) ( 16, 17, 18 ) ( 19, 20, 21 ) ( 22, 23, 24 ) ( 25, 26, 27 ) ( 28, 29, 30 ) ( 31, 32, 33 ) ( 34, 35, 36 ) ( 37, 38, 39 ) ( 40, 41, 42 ) 1 2 3 4 5 6 7 [( 1, 2, 3 ) ( 4, 5, 6 ) , ( 7, 8, 9 ) ( 10, 11, 12 ) ( 13, 14, 15 ) ] [( 16, 17, 18 ) ( 19, 20, 21 ) ( 22, 23, 24 ) , ( 25, 26, 27 ) ( 28, 29, 30 ) , ( 31, 32, 33 ) ( 34, 35, 36 ) ( 37, 38, 39 ) ( 40, 41, 42 ) ] [( 1, 2, 3 ) ( 4, 5, 6 ) , ( 7, 8, 9 ) ( 10, 11, 12 ) ( 13, 14, 15 ) ] */