# Move first element to end of a given Linked List

Write a C function that moves first element to end in a given Singly Linked List. For example, if the given Linked List is 1->2->3->4->5, then the function should change the list to 2->3->4->5->1.

Algorithm:
Traverse the list till last node. Use two pointers: one to store the address of last node(last) and other for address of first node(first). After the end of loop do following operations.
i) Make head as second node (*head_ref = first->next).
ii) Set next of first as NULL (first->next = NULL).
iii) Set next of last as first ( last->next = first)

 `/* C++ Program to move first element to end  ` `   ``in a given linked list */` `#include ` `#include ` ` `  `/* A linked list node */` `struct` `Node { ` `    ``int` `data; ` `    ``struct` `Node* next; ` `}; ` ` `  `/* We are using a double pointer head_ref  ` `   ``here because we change head of the linked  ` `   ``list inside this function.*/` `void` `moveToEnd(``struct` `Node** head_ref) ` `{ ` `    ``/* If linked list is empty, or it contains  ` `       ``only one node, then nothing needs to be  ` `       ``done, simply return */` `    ``if` `(*head_ref == NULL || (*head_ref)->next == NULL) ` `        ``return``; ` ` `  `    ``/* Initialize first and last pointers */` `    ``struct` `Node* first = *head_ref; ` `    ``struct` `Node* last = *head_ref; ` ` `  `    ``/*After this loop last contains address  ` `    ``of last node in Linked List */` `    ``while` `(last->next != NULL) { ` `        ``last = last->next; ` `    ``} ` ` `  `    ``/* Change the head pointer to point  ` `       ``to second node now */` `    ``*head_ref = first->next; ` ` `  `    ``/* Set the next of first as NULL */` `    ``first->next = NULL; ` ` `  `    ``/* Set the next of last as first */` `    ``last->next = first; ` `} ` ` `  `/* UTILITY FUNCTIONS */` `/* Function to add a node at the beginning  ` `   ``of Linked List */` `void` `push(``struct` `Node** head_ref, ``int` `new_data) ` `{ ` `    ``struct` `Node* new_node = ``new` `Node; ` `    ``new_node->data = new_data; ` `    ``new_node->next = (*head_ref); ` `    ``(*head_ref) = new_node; ` `} ` ` `  `/* Function to print nodes in a given linked list */` `void` `printList(``struct` `Node* node) ` `{ ` `    ``while` `(node != NULL) { ` `        ``printf``(``"%d "``, node->data); ` `        ``node = node->next; ` `    ``} ` `} ` ` `  `/* Driver program to test above function */` `int` `main() ` `{ ` `    ``struct` `Node* start = NULL; ` ` `  `    ``/* The constructed linked list is: ` `     ``1->2->3->4->5 */` `    ``push(&start, 5); ` `    ``push(&start, 4); ` `    ``push(&start, 3); ` `    ``push(&start, 2); ` `    ``push(&start, 1); ` ` `  `    ``printf``(``"\n Linked list before moving first to end\n"``); ` `    ``printList(start); ` ` `  `    ``moveToEnd(&start); ` ` `  `    ``printf``(``"\n Linked list after moving first to end\n"``); ` `    ``printList(start); ` ` `  `    ``return` `0; ` `} `

Output:

```Linked list before moving first to end
1 2 3 4 5
Linked list after moving first to end
2 3 4 5 1
```

Time Complexity: O(n) where n is the number of nodes in the given Linked List.

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