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BaroonnPanquesito7
Baroonn
and
Panquesito7
authored
Revised Linked List (#999)
* Addition of Test to LinkedList I noticed an infinite loop when the program asks the user to "Enter the element to be inserted:", and the user enters a wrong input such as "rr". * Revised Tests * Update linked_list.cpp * Update linked_list.cpp * Update linked_list.cpp * Update linked_list.cpp * Update linked_list.cpp * Update linked_list.cpp * Update linked_list.cpp * Update data_structures/linked_list.cpp Co-authored-by: David Leal <[email protected]> * Update data_structures/linked_list.cpp Co-authored-by: David Leal <[email protected]> * Update data_structures/linked_list.cpp Co-authored-by: David Leal <[email protected]> * Update data_structures/linked_list.cpp Co-authored-by: David Leal <[email protected]> * Update data_structures/linked_list.cpp Co-authored-by: David Leal <[email protected]> * Update data_structures/linked_list.cpp Co-authored-by: David Leal <[email protected]> * Update data_structures/linked_list.cpp Co-authored-by: David Leal <[email protected]> * Update linked_list.cpp * Update linked_list.cpp * Update linked_list.cpp * Update data_structures/linked_list.cpp Co-authored-by: David Leal <[email protected]> * added documentations to functions I made a few changes although I'm not sure I covered all. * Update linked_list.cpp * function documentation Co-authored-by: David Leal <[email protected]> * function documentation Co-authored-by: David Leal <[email protected]> * function documentation * Update linked_list.cpp * removed global variable I decided to go with the parameter approach. Is line 79(Iter& ....) and others like it considered healthy code? * removed global variable * Update linked_list.cpp * Update linked_list.cpp * Update linked_list.cpp * Update linked_list.cpp * Update linked_list.cpp * Update linked_list.cpp * Update linked_list.cpp * fixed clang errors * Update linked_list.cpp * Update linked_list.cpp * Update linked_list.cpp * Update linked_list.cpp * Update linked_list.cpp * program rewrite * Update linked_list.cpp * Update linked_list.cpp * Removed extra space * Update linked_list.cpp * Delete vdoubly_linked_list.ico * added documentation * added documentation * added documentation * use of shared_ptr * use of shared_ptr * modified linked list * Update linked_list.cpp * added string header * Update linked_list.cpp * Update linked_list.cpp * Update linked_list.cpp * Update linked_list.cpp * fixed documentation * fixed link class * Update linked_list.cpp * Update linked_list.cpp * Update linked_list.cpp * Update linked_list.cpp * Update linked_list.cpp * Update linked_list.cpp * Update linked_list.cpp * Update linked_list.cpp * fixed link class * fixed runtime error Co-authored-by: David Leal <[email protected]>
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‎data_structures/linked_list.cpp

Lines changed: 234 additions & 93 deletions
Original file line numberDiff line numberDiff line change
@@ -1,134 +1,275 @@
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/**
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* @file
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* @brief Implementation of singly linked list algorithm.
4+
* @details
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* The linked list is a data structure used for holding a sequence of
6+
* values, which can be added, removed and displayed.
7+
* ### Algorithm
8+
* Values can be added by iterating to the end of a list(by following
9+
* the pointers) starting from the first link. Whichever link points to null
10+
* is considered the last link and is pointed to the new value.
11+
*
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* Values can be removed by also iterating through the list. When the node
13+
* containing the value is found, the node pointing to the current node is made
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* to point to the node that the current node is pointing to, and then returning
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* the current node to heap store.
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*/
117
#include <iostream>
18+
#include <memory>
19+
#include <string>
220

3-
struct node {
4-
int val;
5-
node *next;
6-
};
21+
/**
22+
* @namespace data_structures
23+
* @brief Data Structures algorithms
24+
*/
25+
namespace data_structures {
726

8-
node *start;
27+
/**
28+
* @namespace linked_list
29+
* @brief Functions for singly linked list algorithm
30+
*/
31+
namespace linked_list {
932

10-
void insert(int x) {
11-
node *t = start;
12-
node *n = new node;
13-
n->val = x;
14-
n->next = NULL;
15-
if (start != NULL) {
16-
while (t->next != NULL) {
17-
t = t->next;
33+
/**
34+
* This function checks if the string passed consists
35+
* of only digits.
36+
* @param s To be checked if s contains only integers
37+
* @returns true if there are only only digits present in the string
38+
* @returns false if any other character is found
39+
*/
40+
bool isDigit(const std::string& s) {
41+
// function statements here
42+
for (char i : s) {
43+
if (!isdigit(i)) {
44+
return false;
1845
}
19-
t->next = n;
20-
} else {
21-
start = n;
2246
}
47+
return true;
2348
}
2449

25-
void remove(int x) {
26-
if (start == NULL) {
27-
std::cout << "\nLinked List is empty\n";
28-
return;
29-
} else if (start->val == x) {
30-
node *temp = start;
31-
start = start->next;
32-
delete temp;
33-
return;
50+
/**
51+
* A link class containing a value and pointer to another link
52+
*/
53+
class link {
54+
private:
55+
int pvalue; ///< value of the current link
56+
std::shared_ptr<link> psucc; ///< pointer to the next value on the list
57+
58+
public:
59+
/**
60+
* function returns the integer value stored in the link.
61+
* @returns the integer value stored in the link.
62+
*/
63+
int val() { return pvalue; }
64+
65+
/**
66+
* function returns the pointer to next link
67+
* @returns the pointer to the next link
68+
* */
69+
std::shared_ptr<link>& succ() { return psucc; }
70+
71+
/**
72+
* Creates link with provided value and pointer to next link
73+
* @param value is the integer stored in the link
74+
*/
75+
explicit link(int value = 0) : pvalue(value), psucc(nullptr) {}
76+
};
77+
78+
/**
79+
* A list class containing a sequence of links
80+
*/
81+
class list {
82+
private:
83+
std::shared_ptr<link> first; ///< link before the actual first element
84+
std::shared_ptr<link> last; ///< last link on the list
85+
public:
86+
/**
87+
* List constructor. Initializes the first and last link.
88+
*/
89+
list() {
90+
// Initialize the first link
91+
first = std::make_shared<link>();
92+
// Initialize the last link with the first link
93+
last = nullptr;
3494
}
3595

36-
node *temp = start, *parent = start;
96+
bool isEmpty();
97+
98+
void push_back(int new_elem);
99+
void push_front(int new_elem);
100+
void erase(int old_elem);
101+
void display();
102+
std::shared_ptr<link> search(int find_elem);
103+
void reverse();
104+
};
37105

38-
while (temp != NULL && temp->val != x) {
39-
parent = temp;
40-
temp = temp->next;
106+
/**
107+
* function checks if list is empty
108+
* @returns true if list is empty
109+
* @returns false if list is not empty
110+
*/
111+
bool list::isEmpty() {
112+
if (last == nullptr) {
113+
return true;
114+
} else {
115+
return false;
41116
}
117+
}
42118

43-
if (temp == NULL) {
44-
std::cout << std::endl << x << " not found in list\n";
45-
return;
119+
/**
120+
* function adds new element to the end of the list
121+
* @param new_elem to be added to the end of the list
122+
*/
123+
void list::push_back(int new_elem) {
124+
if (isEmpty()) {
125+
first->succ() = std::make_shared<link>(new_elem);
126+
last = first->succ();
127+
} else {
128+
last->succ() = std::make_shared<link>(new_elem);
129+
last = last->succ();
46130
}
131+
}
47132

48-
parent->next = temp->next;
49-
delete temp;
133+
/**
134+
* function adds new element to the beginning of the list
135+
* @param new_elem to be added to front of the list
136+
*/
137+
void list::push_front(int new_elem) {
138+
if (isEmpty()) {
139+
first->succ() = std::make_shared<link>(new_elem);
140+
last = first->succ();
141+
} else {
142+
std::shared_ptr<link> t = std::make_shared<link>(new_elem);
143+
t->succ() = first->succ();
144+
first->succ() = t;
145+
}
50146
}
51147

52-
void search(int x) {
53-
node *t = start;
54-
int found = 0;
55-
while (t != NULL) {
56-
if (t->val == x) {
57-
std::cout << "\nFound";
58-
found = 1;
59-
break;
60-
}
61-
t = t->next;
148+
/**
149+
* function erases old element from the list
150+
* @param old_elem to be erased from the list
151+
*/
152+
void list::erase(int old_elem) {
153+
if (isEmpty()) {
154+
std::cout << "List is Empty!";
155+
return;
62156
}
63-
if (found == 0) {
64-
std::cout << "\nNot Found";
157+
std::shared_ptr<link> t = first;
158+
std::shared_ptr<link> to_be_removed = nullptr;
159+
while (t != last && t->succ()->val() != old_elem) {
160+
t = t->succ();
161+
}
162+
if (t == last) {
163+
std::cout << "Element not found\n";
164+
return;
165+
}
166+
to_be_removed = t->succ();
167+
t->succ() = t->succ()->succ();
168+
to_be_removed.reset();
169+
if (t->succ() == nullptr) {
170+
last = nullptr;
65171
}
66172
}
67173

68-
void show() {
69-
node *t = start;
70-
while (t != NULL) {
71-
std::cout << t->val << "\t";
72-
t = t->next;
174+
/**
175+
* function displays all the elements in the list
176+
* @returns 'void'
177+
*/
178+
void list::display() {
179+
if (isEmpty()) {
180+
std::cout << "List is Empty!";
181+
return;
182+
}
183+
std::shared_ptr<link> t = first;
184+
while (t->succ() != nullptr) {
185+
std::cout << t->succ()->val() << "\t";
186+
t = t->succ();
73187
}
74188
}
75189

76-
void reverse() {
77-
node *first = start;
78-
if (first != NULL) {
79-
node *second = first->next;
80-
while (second != NULL) {
81-
node *tem = second->next;
82-
second->next = first;
83-
first = second;
84-
second = tem;
85-
}
86-
start->next = NULL;
87-
start = first;
88-
} else {
89-
std::cout << "\nEmpty list";
190+
/**
191+
* function searchs for @param find_elem in the list
192+
* @param find_elem to be searched for in the list
193+
*/
194+
std::shared_ptr<link> list::search(int find_elem) {
195+
if (isEmpty()) {
196+
std::cout << "List is Empty!";
197+
return nullptr;
198+
}
199+
std::shared_ptr<link> t = first;
200+
while (t != last && t->succ()->val() != find_elem) {
201+
t = t->succ();
90202
}
203+
if (t == last) {
204+
std::cout << "Element not found\n";
205+
return nullptr;
206+
}
207+
std::cout << "Element was found\n";
208+
return t->succ();
91209
}
210+
} // namespace linked_list
211+
} // namespace data_structures
92212

213+
/**
214+
* Main function:
215+
* Allows the user add and delete values from the list.
216+
* Also allows user to search for and display values in the list.
217+
* @returns 0 on exit
218+
*/
93219
int main() {
94-
int choice, x;
220+
data_structures::linked_list::list l;
221+
int choice = 0;
222+
int x = 0;
223+
std::string s;
95224
do {
96225
std::cout << "\n1. Insert";
97226
std::cout << "\n2. Delete";
98227
std::cout << "\n3. Search";
99228
std::cout << "\n4. Print";
100-
std::cout << "\n5. Reverse";
101229
std::cout << "\n0. Exit";
102230
std::cout << "\n\nEnter you choice : ";
103231
std::cin >> choice;
104232
switch (choice) {
105-
case 1:
106-
std::cout << "\nEnter the element to be inserted : ";
107-
std::cin >> x;
108-
insert(x);
109-
break;
110-
case 2:
111-
std::cout << "\nEnter the element to be removed : ";
112-
std::cin >> x;
113-
remove(x);
114-
break;
115-
case 3:
116-
std::cout << "\nEnter the element to be searched : ";
117-
std::cin >> x;
118-
search(x);
119-
break;
120-
case 4:
121-
show();
122-
std::cout << "\n";
123-
break;
124-
case 5:
125-
std::cout << "The reversed list: \n";
126-
reverse();
127-
show();
128-
std::cout << "\n";
129-
break;
233+
case 1:
234+
std::cout << "\nEnter the element to be inserted : ";
235+
std::cin >> s;
236+
237+
if (data_structures::linked_list::isDigit(s)) {
238+
x = std::stoi(s);
239+
l.push_back(x);
240+
} else {
241+
std::cout << "Wrong Input!\n";
242+
}
243+
break;
244+
case 2:
245+
std::cout << "\nEnter the element to be removed : ";
246+
std::cin >> s;
247+
if (data_structures::linked_list::isDigit(s)) {
248+
x = std::stoi(s);
249+
l.erase(x);
250+
} else {
251+
std::cout << "Wrong Input!\n";
252+
}
253+
break;
254+
case 3:
255+
std::cout << "\nEnter the element to be searched : ";
256+
std::cin >> s;
257+
if (data_structures::linked_list::isDigit(s)) {
258+
x = std::stoi(s);
259+
std::shared_ptr<data_structures::linked_list::link> found =
260+
l.search(x);
261+
} else {
262+
std::cout << "Wrong Input!\n";
263+
}
264+
break;
265+
case 4:
266+
l.display();
267+
std::cout << "\n";
268+
break;
269+
default:
270+
std::cout << "Invalid Input\n" << std::endl;
271+
break;
130272
}
131273
} while (choice != 0);
132-
133274
return 0;
134275
}

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