rotateALinkedlist.cpp

Linked List/rotateALinkedlist.cpp

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+// C++ program to rotate
+// a linked list counter clock wise
+
+#include <bits/stdc++.h>
+using namespace std;
+
+/* Link list node */
+class Node {
+public:
+	int data;
+	Node* next;
+};
+
+// This function rotates a linked list
+// counter-clockwise and updates the
+// head. The function assumes that k is
+// smaller than size of linked list.
+// It doesn't modify the list if
+// k is greater than or equal to size
+void rotate(Node** head_ref, int k)
+{
+	if (k == 0)
+		return;
+
+	Node* current = *head_ref;
+
+	int count = 1;
+	while (count < k && current != NULL) {
+		current = current->next;
+		count++;
+	}
+
+	if (current == NULL)
+		return;
+
+	Node* kthNode = current;
+
+	while (current->next != NULL)
+		current = current->next;
+
+	current->next = *head_ref;
+
+	*head_ref = kthNode->next;
+
+	kthNode->next = NULL;
+}
+
+/* Function to push a node */
+void push(Node** head_ref, int new_data)
+{
+	/* allocate node */
+	Node* new_node = new Node();
+
+	/* put in the data */
+	new_node->data = new_data;
+
+	/* link the old list off the new node */
+	new_node->next = (*head_ref);
+
+	/* move the head to point to the new node */
+	(*head_ref) = new_node;
+}
+
+/* Function to print linked list */
+void printList(Node* node)
+{
+	while (node != NULL) {
+		cout << node->data << " ";
+		node = node->next;
+	}
+}
+
+int main()
+{
+	/* Start with the empty list */
+	Node* head = NULL;
+
+	// create a list 10->20->30->40->50->60
+	for (int i = 60; i > 0; i -= 10)
+		push(&head, i);
+
+	cout << "Given linked list \n";
+	printList(head);
+	rotate(&head, 4);
+
+	cout << "\nRotated Linked list \n";
+	printList(head);
+
+	return (0);
+}