Create Copy of Singly Linked List

1#include <stdio.h>
2#include <stdlib.h>
3
4struct Node {
5    int data;
6    struct Node *next;
7};
8
9// Create new node
10struct Node* createNode(int data) {
11    struct Node *node = (struct Node*)malloc(sizeof(struct Node));
12    node->data = data;
13    node->next = NULL;
14    return node;
15}
16
17// Recursively copy linked list
18struct Node* copyList(struct Node *head) {
19    if (head == NULL) return NULL;
20    
21    struct Node *newNode = createNode(head->data);
22    newNode->next = copyList(head->next);
23    
24    return newNode;
25}
26
27// Print list
28void printList(struct Node *head) {
29    while (head != NULL) {
30        printf("%d -> ", head->data);
31        head = head->next;
32    }
33    printf("NULL\n");
34}
35
36int main() {
37    // Create original list: 1 -> 2 -> 3 -> 4 -> NULL
38    struct Node *head = createNode(1);
39    head->next = createNode(2);
40    head->next->next = createNode(3);
41    head->next->next->next = createNode(4);
42    
43    printf("Original list: ");
44    printList(head);
45    
46    // Copy list
47    struct Node *copy = copyList(head);
48    
49    printf("Copied list:   ");
50    printList(copy);
51    
52    // Modify original to prove copy is independent
53    head->data = 100;
54    printf("\nAfter modifying original:\n");
55    printf("Original: ");
56    printList(head);
57    printf("Copy:     ");
58    printList(copy);
59    
60    return 0;
61}