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LinkedList/kSort.cpp

@@ -13,6 +13,8 @@ if we find it is smaller then insert
 
 
 * We are doing on O(nlogk) approach -> code below*
+
+mean heap gives lowest value max heap gives highest value
 */
 
 #include <bits/stdc++.h>
@@ -76,7 +78,7 @@ struct compare //{changing to min heap}
 {
     bool operator()(node *first, node *second)
     {
-        return first->data > second->data;
+        return first->data > second->data; // gives  ascending
     }
 };
 node *kSort(node *&head, int k)

LinkedList/rotaten.cpp

@@ -0,0 +1,112 @@
+/*
+Rotate Doubly linked list by N nodes
+
+Given a doubly linked list, rotate the linked list counter-clockwise by N nodes. 
+Here N is a given positive integer and is smaller than the count of nodes in linked list. 
+
+input 1,2,3,4,5
+output 3,4,5,1,2
+*/
+
+#include <bits/stdc++.h>
+using namespace std;
+
+class node
+{
+public:
+    int data;
+    node *next;
+    node *prev; //for dll
+
+    node(int val)
+    { //constructor
+        data = val;
+        next = NULL;
+        prev = NULL; //for dll
+    }
+};
+
+void insertAtHead(node *&head, int val)
+{
+    node *n = new node(val);
+    n->next = head;
+    if (head != NULL) //if head is there then only we can point to prev
+    {
+        head->prev = n; //for dll
+    }
+    head = n;
+}
+
+void insertAtTail(node *&head, int val) //head by ref and not by val because we have to mod ll
+{
+    node *n = new node(val);
+    if (head == NULL)
+    {
+        insertAtHead(head, val);
+        return;
+    }
+    node *temp = head; //iterator (will traverse the ll)
+    while (temp->next != NULL)
+    {
+        temp = temp->next;
+    }               //we are at last element now
+    temp->next = n; // n->next has already value NULL
+    n->prev = temp; // for dll
+}
+
+void display(node *head) //head by value because wea re not mod ll
+{
+    node *temp = head;
+    while (temp != NULL)
+    {
+        cout << temp->data << " ";
+        temp = temp->next;
+    }
+    cout << endl;
+}
+
+node *rotateN(node *&head, int n)
+{ //head is pointing 1
+    if (n == 0)
+    {
+        return head;
+    }
+    node *temp = head; //iterator
+    int count = 1;
+    while (count < n and temp != NULL)
+    {
+        temp = temp->next;
+        count++;
+    }
+    node *newHead = temp; //pointing 2 as per example
+    while (temp->next != NULL)
+    {
+        temp = temp->next; //sending to last element
+    }                      //temp pointing 5
+
+    //connecting points
+
+    temp->next = head;    //5 next is 1
+    head->prev = temp;    //1 prev is 5
+    head = newHead->next; //new head is 3
+    head->prev = NULL;    //prev of 3 pointing NULL
+    newHead->next = NULL; //2 next is null
+
+    return head;
+}
+
+int main()
+{
+    int n = 2;
+    node *head = NULL;
+    insertAtTail(head, 1);
+    insertAtTail(head, 2);
+    insertAtTail(head, 3);
+    insertAtTail(head, 4);
+    insertAtTail(head, 5);
+    display(head);
+    head = rotateN(head, n);
+    display(head);
+
+    return 0;
+}