rotate-linkedList.cpp

#include <stdio.h>
#include <stdlib.h>

struct Node {
    int data;
    struct Node* next;
};

// This function rotates a linked list counter-clockwise
void rotate(struct Node** head_ref, int k)
{
    if (k == 0)
        return;

    struct Node* current = *head_ref;

    int count = 1;
    while (count < k && current != NULL) {
        current = current->next;
        count++;
    }

    if (current == NULL)
        return;

    struct Node* kthNode = current;

    while (current->next != NULL)
        current = current->next;

    current->next = *head_ref;

    *head_ref = kthNode->next;

    kthNode->next = NULL;
}

void push(struct Node** head_ref, int new_data)
{
    struct Node* new_node
        = (struct Node*)malloc(sizeof(struct Node));

    new_node->data = new_data;

    new_node->next = (*head_ref);

    (*head_ref) = new_node;
}

void printList(struct Node* node)
{
    while (node != NULL) {
        printf("%d ", node->data);
        node = node->next;
    }
}

int main(void)
{
    struct Node* head = NULL;

    for (int i = 60; i > 0; i -= 10)
        push(&head, i);

    printf("Given linked list \n");
    printList(head);
    rotate(&head, 4);

    printf("\nRotated Linked list \n");
    printList(head);

    return (0);
}