└── SINGLY LINKED LIST AND ITS OPERATIONS.cpp


/SINGLY LINKED LIST AND ITS OPERATIONS.cpp:
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  1 | #include <bits/stdc++.h>
  2 | using namespace std;
  3 | class Node
  4 | {
  5 |     public:
  6 |         int key;
  7 |         Node* next;
  8 | };
  9 | Node* newnode(int data)
 10 | {
 11 |     Node* n = new Node();
 12 |     n->key = data;
 13 |     n->next = NULL;
 14 |     return n;
 15 | }
 16 | Node* insert_begin(int data,Node* head)
 17 | {
 18 |     Node* nn = newnode(data);
 19 |     if(head == NULL)
 20 |     { 
 21 |         head = nn;
 22 |     }
 23 |     else
 24 |     {
 25 |         nn->next = head;
 26 |         head = nn;
 27 |     }
 28 |     return head;
 29 | }
 30 | Node* insert_end(int data,Node* head)
 31 | {
 32 |     Node* nn = newnode(data);
 33 |     if(head == NULL)
 34 |     {
 35 |         head = nn;
 36 |     }
 37 |     else
 38 |     {
 39 |         Node* temp = head;
 40 |         while(temp->next != NULL)
 41 |         {
 42 |             temp = temp->next;
 43 |         }
 44 |         temp->next = nn;
 45 |     }
 46 |     return head;
 47 | }
 48 | Node* insert_mid(int data,Node* head,int pos)
 49 | {
 50 |     Node* nn = newnode(data);
 51 |     if(head == NULL)
 52 |     {
 53 |         head = nn;
 54 |     }
 55 |     else if(pos==1)
 56 |     {
 57 |         Node* temp = head;
 58 |         nn->next = head;
 59 |         head = nn;
 60 |     }
 61 |     else
 62 |     {
 63 |         int count = 1;
 64 |         Node* temp = head;
 65 |         while(temp->next != NULL)
 66 |         {
 67 |             count++;
 68 |             if(count == pos)
 69 |             {
 70 |                 break;
 71 |             }
 72 |             temp = temp->next;
 73 |         }
 74 |         if(count == pos)
 75 |         {
 76 |             nn->next = temp->next;
 77 |             temp->next = nn;
 78 |         }
 79 |         else
 80 |         {
 81 |             cout << "Invalid" << " ";
 82 |         }
 83 |     }
 84 |     return head;
 85 | }
 86 | Node* display(Node* head)
 87 | {
 88 |     Node*temp = head;
 89 |     while(temp != NULL)
 90 |     {
 91 |         cout << temp->key << " ";
 92 |         temp = temp->next;
 93 |     }
 94 |     cout << NULL << " " << endl;
 95 |     return head;
 96 | }
 97 | Node* delete_node(Node* head)
 98 | {
 99 |     Node* temp = head;
100 |     if(head == NULL)
101 |     {
102 |         cout << "Invalid" << " ";
103 |     }
104 |     else if(head->next == NULL)
105 |     {
106 |         head = NULL;
107 |     }
108 |     else
109 |     {
110 |         while(temp->next->next != NULL)
111 |         {
112 |             temp = temp->next;
113 |         }
114 |         temp->next = NULL;
115 |     }
116 |     return head;
117 | }
118 | Node* delete_first(Node* head)
119 | {
120 |     if(head == NULL)
121 |     {
122 |         cout << "Invalid" << " ";
123 |     }
124 |     else
125 |     {
126 |         head = head->next;
127 |     }
128 |     return head;
129 | }
130 | Node* delete_pos(int pos,Node* head)
131 | {
132 |     if(head == NULL)
133 |     {
134 |         cout << "Invalid" << " ";
135 |     }
136 |     else if(pos == 1)
137 |     {
138 |         head = delete_first(head);
139 |     }
140 |     else
141 |     {
142 |         int count = 1;
143 |         Node* temp = head;
144 |         while(temp != NULL)
145 |         {
146 |             Node* temp1 = temp->next;
147 |             count++;
148 |             if(count == pos)
149 |             {
150 |                 temp->next = temp1->next;
151 |                 //temp1->next = NULL;
152 |                 break;
153 |             }
154 |             temp = temp->next;
155 |         }
156 |     }
157 |     return head;
158 | }
159 | bool search_element(int data,Node* head)
160 | {
161 |     if(head == NULL)
162 |     {
163 |         cout << "Not found" << " ";
164 |     }
165 |     else
166 |     {
167 |         Node* temp = head;
168 |         while(temp != NULL)
169 |         {
170 |             if(temp->key == data)
171 |             {
172 |                 return true;
173 |             }
174 |             temp = temp->next;
175 |         }
176 |     }
177 |     return false;
178 | }
179 | Node* displayreverse(Node* head)
180 | {
181 |     if(head==NULL)
182 |     {
183 |         cout << "No elements" << " ";
184 |     }
185 |     else if(head->next == NULL)
186 |     {
187 |         cout << "Only one element";
188 |     }
189 |     else
190 |     {
191 |         Node* temp1 = NULL;
192 |         Node* temp2 = head;
193 |         Node* temp3 = head->next;
194 |         while(temp3!=NULL)
195 |         {
196 |             temp2->next = temp1;
197 |             temp1 = temp2;
198 |             temp2 = temp3;
199 |             temp3 = temp2->next;
200 |         }
201 |         temp2->next = temp1;
202 |         head = temp2;
203 |     }
204 |     return head;
205 | }
206 | int main() {
207 | 	Node* head = NULL;
208 | 	head = insert_begin(100,head);
209 | 	head = insert_begin(90,head);
210 | 	head = insert_end(110,head);
211 | 	head = insert_end(120,head);
212 | 	head = insert_end(130,head);
213 | 	head = insert_begin(80,head);
214 | 	head = insert_mid(70,head,1);
215 | 	//head = delete_node(head);
216 | 	//head = delete_pos(1,head);
217 | 	//head = delete_first(head);
218 | 	//bool a = search_element(110,head);
219 | 	//cout << "Searching result:" << a << endl;
220 | 	head = display(head);
221 | 	head = displayreverse(head);
222 | 	head = display(head);
223 | 	return 0;
224 | }
225 | 


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