singly linked list all operations

data_structures/linked_list/singly_link_list.c

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+/**
+ * @file singly_linked_list.c
+ * @brief Implementation of a singly linked list in C.
+ *
+ * This file implements a singly linked list with the following operations:
+ * 1. Insert at the beginning
+ * 2. Insert at the end
+ * 3. Insert at a specific position
+ * 4. Delete from the beginning
+ * 5. Delete from the end
+ * 6. Delete from a specific position
+ * 7. Display the linked list
+ *
+ * Time Complexity:
+ *   - Insert at beginning: O(1)
+ *   - Insert at end: O(n)
+ *   - Insert at position: O(n)
+ *   - Delete at beginning: O(1)
+ *   - Delete at end: O(n)
+ *   - Delete at position: O(n)
+ *   - Display: O(n)
+ *
+ * Author: Rahul Guggilam
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+/** Node structure for singly linked list */
+typedef struct Node
+{
+    int data;
+    struct Node* next;
+} Node;
+
+/** Function to create a new node with given data */
+Node* create_node(int data)
+{
+    Node* new_node = (Node*)malloc(sizeof(Node));
+    if (!new_node)
+    {
+        printf("Memory allocation failed\n");
+        exit(EXIT_FAILURE);
+    }
+    new_node->data = data;
+    new_node->next = NULL;
+    return new_node;
+}
+
+/** Insert a node at the beginning of the linked list */
+void insert_begin(Node** head, int data)
+{
+    Node* new_node = create_node(data);
+    new_node->next = *head;
+    *head = new_node;
+}
+
+/** Insert a node at the end of the linked list */
+void insert_end(Node** head, int data)
+{
+    Node* new_node = create_node(data);
+    if (*head == NULL)
+    {
+        *head = new_node;
+        return;
+    }
+    Node* temp = *head;
+    while (temp->next != NULL)
+    {
+        temp = temp->next;
+    }
+    temp->next = new_node;
+}
+
+/** Insert a node at a specific position (1-based index) */
+void insert_position(Node** head, int data, int position)
+{
+    if (position < 1)
+    {
+        printf("Invalid position\n");
+        return;
+    }
+    if (position == 1)
+    {
+        insert_begin(head, data);
+        return;
+    }
+    Node* temp = *head;
+    for (int i = 1; i < position - 1 && temp != NULL; i++)
+    {
+        temp = temp->next;
+    }
+    if (temp == NULL)
+    {
+        printf("Position exceeds list length, inserting at end\n");
+        insert_end(head, data);
+        return;
+    }
+    Node* new_node = create_node(data);
+    new_node->next = temp->next;
+    temp->next = new_node;
+}
+
+/** Delete the first node of the linked list */
+void delete_begin(Node** head)
+{
+    if (*head == NULL)
+    {
+        printf("List is empty\n");
+        return;
+    }
+    Node* temp = *head;
+    *head = (*head)->next;
+    free(temp);
+}
+
+/** Delete the last node of the linked list */
+void delete_end(Node** head)
+{
+    if (*head == NULL)
+    {
+        printf("List is empty\n");
+        return;
+    }
+    if ((*head)->next == NULL)
+    {
+        free(*head);
+        *head = NULL;
+        return;
+    }
+    Node* temp = *head;
+    while (temp->next->next != NULL)
+    {
+        temp = temp->next;
+    }
+    free(temp->next);
+    temp->next = NULL;
+}
+
+/** Delete a node at a specific position (1-based index) */
+void delete_position(Node** head, int position)
+{
+    if (*head == NULL || position < 1)
+    {
+        printf("Invalid position or empty list\n");
+        return;
+    }
+    if (position == 1)
+    {
+        delete_begin(head);
+        return;
+    }
+    Node* temp = *head;
+    for (int i = 1; i < position - 1 && temp->next != NULL; i++)
+    {
+        temp = temp->next;
+    }
+    if (temp->next == NULL)
+    {
+        printf("Position exceeds list length\n");
+        return;
+    }
+    Node* del_node = temp->next;
+    temp->next = del_node->next;
+    free(del_node);
+}
+
+/** Display all nodes in the linked list */
+void display(Node* head)
+{
+    if (head == NULL)
+    {
+        printf("List is empty\n");
+        return;
+    }
+    Node* temp = head;
+    printf("Linked list: ");
+    while (temp != NULL)
+    {
+        printf("%d -> ", temp->data);
+        temp = temp->next;
+    }
+    printf("NULL\n");
+}
+
+/** Main function demonstrating linked list operations */
+int main()
+{
+    Node* head = NULL;
+    int choice, data, pos;
+
+    while (1)
+    {
+        printf(
+            "\n1. Insert at beginning\n2. Insert at end\n3. Insert at "
+            "position\n");
+        printf(
+            "4. Delete at beginning\n5. Delete at end\n6. Delete at "
+            "position\n7. Display\n8. Exit\n");
+        printf("Enter your choice: ");
+        scanf("%d", &choice);
+
+        switch (choice)
+        {
+        case 1:
+            printf("Enter data: ");
+            scanf("%d", &data);
+            insert_begin(&head, data);
+            break;
+        case 2:
+            printf("Enter data: ");
+            scanf("%d", &data);
+            insert_end(&head, data);
+            break;
+        case 3:
+            printf("Enter data and position: ");
+            scanf("%d %d", &data, &pos);
+            insert_position(&head, data, pos);
+            break;
+        case 4:
+            delete_begin(&head);
+            break;
+        case 5:
+            delete_end(&head);
+            break;
+        case 6:
+            printf("Enter position to delete: ");
+            scanf("%d", &pos);
+            delete_position(&head, pos);
+            break;
+        case 7:
+            display(head);
+            break;
+        case 8:
+            printf("Exiting...\n");
+            exit(0);
+        default:
+            printf("Invalid choice\n");
+        }
+    }
+    return 0;
+}