singly linked list insertions and other operations

Author: jbhavya11

singly linked list/singly-linked-list.cpp

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+// A complete working C++ program to demonstrate 
+// all insertion methods on Linked List 
+#include <bits/stdc++.h> 
+using namespace std; 
+
+// A linked list node 
+class Node 
+{ 
+	public: 
+	int data; 
+	Node *next; 
+}; 
+
+/* Given a reference (pointer to pointer) 
+to the head of a list and an int, inserts 
+a new node on the front of the list. */
+void push(Node** head_ref, int new_data) 
+{ 
+	/* 1. allocate node */
+	Node* new_node = new Node(); 
+
+	/* 2. put in the data */
+	new_node->data = new_data; 
+
+	/* 3. Make next of new node as head */
+	new_node->next = (*head_ref); 
+
+	/* 4. move the head to point to the new node */
+	(*head_ref) = new_node; 
+} 
+
+/* Given a node prev_node, insert a new node after the given 
+prev_node */
+void insertAfter(Node* prev_node, int new_data) 
+{ 
+	/*1. check if the given prev_node is NULL */
+	if (prev_node == NULL) 
+	{ 
+		cout<<"the given previous node cannot be NULL"; 
+		return; 
+	} 
+
+	/* 2. allocate new node */
+	Node* new_node = new Node(); 
+
+	/* 3. put in the data */
+	new_node->data = new_data; 
+
+	/* 4. Make next of new node as next of prev_node */
+	new_node->next = prev_node->next; 
+
+	/* 5. move the next of prev_node as new_node */
+	prev_node->next = new_node; 
+} 
+
+/* Given a reference (pointer to pointer) to the head 
+of a list and an int, appends a new node at the end */
+void append(Node** head_ref, int new_data) 
+{ 
+	/* 1. allocate node */
+	Node* new_node = new Node(); 
+
+	Node *last = *head_ref; /* used in step 5*/
+
+	/* 2. put in the data */
+	new_node->data = new_data; 
+
+	/* 3. This new node is going to be 
+	the last node, so make next of 
+	it as NULL*/
+	new_node->next = NULL; 
+
+	/* 4. If the Linked List is empty, 
+	then make the new node as head */
+	if (*head_ref == NULL) 
+	{ 
+		*head_ref = new_node; 
+		return; 
+	} 
+
+	/* 5. Else traverse till the last node */
+	while (last->next != NULL) 
+		last = last->next; 
+
+	/* 6. Change the next of last node */
+	last->next = new_node; 
+	return; 
+} 
+
+// This function prints contents of 
+// linked list starting from head 
+void printList(Node *node) 
+{ 
+	while (node != NULL) 
+	{ 
+		cout<<" "<<node->data; 
+		node = node->next; 
+	} 
+} 
+
+/* Driver code*/
+int main() 
+{ 
+	/* Start with the empty list */
+	Node* head = NULL; 
+	
+	// Insert 6. So linked list becomes 6->NULL 
+	append(&head, 6); 
+	
+	// Insert 7 at the beginning. 
+	// So linked list becomes 7->6->NULL 
+	push(&head, 7); 
+	
+	// Insert 1 at the beginning. 
+	// So linked list becomes 1->7->6->NULL 
+	push(&head, 1); 
+	
+	// Insert 4 at the end. So 
+	// linked list becomes 1->7->6->4->NULL 
+	append(&head, 4); 
+	
+	// Insert 8, after 7. So linked 
+	// list becomes 1->7->8->6->4->NULL 
+	insertAfter(head->next, 8); 
+	
+	cout<<"Created Linked list is: "; 
+	printList(head); 
+	
+	return 0; 
+} 
+
+
+// This code is contributed by rathbhupendra