Question

Add the following methods to the singly list implementation below.

int size(); // Returns the number of nodes in the linked list
bool search(string query); // Returns if the query is present in the list
void add(List& l); // // Adds elements of input list to front of "this" list (the list that calls the add method)

#include <string>

#include "slist.h"

using namespace std;

Node::Node(string element) : data{element}, next{nullptr} {}

List::List() : first{nullptr} {}

// Adds to the front of the list

void List::pushFront(string element) {

Node* new_node = new Node(element);

if (first == nullptr) {// List is empty

first = new_node;

} else {

new_node->next = first;

first = new_node;

}

}

Iterator List::begin() {

Iterator iter;

iter.position = first;

iter.container = this;

return iter;

}

Iterator List::end() {

Iterator iter;

iter.position = nullptr;

iter.container = this;

return iter;

}

// Returns number of elements in the list

int List::size() {

// Q1: Your code here

}

// Returns if query is present in list (true/false)

bool List::search(string query) {

// Q2: Your code here

}

// Adds elements of input list to front of "this" list

void List::add(List& l) {

// Q3. Your code here

}

Iterator::Iterator() {

position = nullptr;

container = nullptr;

}

string Iterator::get() const {

return position->data;

}

void Iterator::next() {

position = position->next;

}

bool Iterator::equals(Iterator other) const {

return position == other.position;

}

------------------------------------------------------------------------------------Header File

/* Singly linked list */

#ifndef LIST_H

#define LIST_H

#include <string>

using namespace std;

class List;

class Iterator;

class Node

{

public:

Node(string element);

private:

string data;

Node* previous;

Node* next;

friend class List;

friend class Iterator;

};

class List

{

public:

List();

void pushFront(string element);

Iterator begin();

Iterator end();

int size();

bool search(string query);

void add(List& l);

private:

Node* first;

friend class Iterator;

};

class Iterator

{

public:

Iterator();

string get() const;

void next();

bool equals(Iterator other) const;

private:

Node* position;

List* container;

friend class List;

};

#endif

-------------------------------------------------------------------------------------------------------test file

#include <string>

#include <iostream>

#include "slist.h"

using namespace std;

int main()

{

List names1;

names1.pushFront("Alice");

names1.pushFront("Bob");

names1.pushFront("Carol");

names1.pushFront("David");

// names1 is now - David Carol Bob Alice

int numele = names1.size(); // Q1: TO BE COMPLETED

cout << "Number of elements in the list: " << numele << endl;

string query = "Eve";

bool present = names1.search(query); // Q2: TO BE COMPLETED

if (present) {

cout << query << " is present" << endl;

} else {

cout << query << " is absent" << endl;

}

List names2;

names2.pushFront("Eve");

names2.pushFront("Fred");

// names2 is now - Fred Eve

// Insert each element of input list (names1) to front of calling list (names2)

names2.add(names1); // Q3: TO BE COMPLETED

// Print extended list

// Should print - Alice Bob Carol David Fred Eve

for (Iterator pos = names2.begin(); !pos.equals(names2.end()); pos.next()) {

cout << pos.get() << " ";

}

cout << endl;

return 0;

}

Answer 1

#######################################
            main.cpp
#######################################
#include <string>

#include <iostream>

#include "slist.h"

using namespace std;

int main()

{

List names1;

names1.pushFront("Alice");

names1.pushFront("Bob");

names1.pushFront("Carol");

names1.pushFront("David");

// names1 is now - David Carol Bob Alice

int numele = names1.size(); // Q1: TO BE COMPLETED

cout << "Number of elements in the list: " << numele << endl;

string query = "Eve";

bool present = names1.search(query); // Q2: TO BE COMPLETED

if (present) {

cout << query << " is present" << endl;

} else {

cout << query << " is absent" << endl;

}

List names2;

names2.pushFront("Eve");

names2.pushFront("Fred");

// names2 is now - Fred Eve

// Insert each element of input list (names1) to front of calling list (names2)

names2.add(names1); // Q3: TO BE COMPLETED

// Print extended list

// Should print - Alice Bob Carol David Fred Eve

for (Iterator pos = names2.begin(); !pos.equals(names2.end()); pos.next()) {

cout << pos.get() << " ";

}

cout << endl;

return 0;

}



#######################################
           slist.cpp
#######################################
#include <string>

#include "slist.h"

using namespace std;

Node::Node(string element) : data(element), next(nullptr) {}

List::List() : first(nullptr) {}

// Adds to the front of the list

void List::pushFront(string element) {

Node* new_node = new Node(element);

if (first == nullptr) {// List is empty

first = new_node;

} else {

new_node->next = first;

first = new_node;

}

}

Iterator List::begin() {

Iterator iter;

iter.position = first;

iter.container = this;

return iter;

}

Iterator List::end() {

Iterator iter;

iter.position = nullptr;

iter.container = this;

return iter;

}

// Returns number of elements in the list

int List::size() {
    int count = 0;
    Node *start = first;
    while(start != nullptr) {
        count++;
        start = start->next;
    }
    return count;
}

// Returns if query is present in list (true/false)
bool List::search(string query) {
    Node *start = first;
    while(start != nullptr) {
        if(start->data == query) {
            return true;
        }
        start = start->next;
    }
    return false;
}

// Adds elements of input list to front of "this" list
void List::add(List& l) {
    Node *start = l.first;
    while(start != nullptr) {
        pushFront(start->data);
        start = start->next;
    }
}

Iterator::Iterator() {

position = nullptr;

container = nullptr;

}

string Iterator::get() const {

return position->data;

}

void Iterator::next() {

position = position->next;

}

bool Iterator::equals(Iterator other) const {

return position == other.position;

}



#######################################
             slist.h
#######################################
/* Singly linked list */
#ifndef LIST_H
#define LIST_H

#include <string>

using namespace std;

class List;
class Iterator;

class Node {

public:

Node(string element);

private:

string data;

Node* previous;

Node* next;

friend class List;

friend class Iterator;

};

class List

{

public:

List();

void pushFront(string element);

Iterator begin();

Iterator end();

int size();

bool search(string query);

void add(List& l);

private:

Node* first;

friend class Iterator;

};

class Iterator

{

public:

Iterator();

string get() const;

void next();

bool equals(Iterator other) const;

private:

Node* position;

List* container;

friend class List;

};

#endif

**************************************************

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