JRSETI Wiki

Good Binary Heap Tutorial

enqueue or dequeue items in O(logn)

Priority Queues use a min heap or max heap

prev = None
cur = head
while cur:
  next_node = cur.next
  cur.next = prev
  prev = cur
  cur = next_node
head = prev

void reverse() { 
        Node temp = null; 
        Node current = head; 
  
        /* swap next and prev for all nodes of  
         doubly linked list */
        while (current != null) { 
            temp = current.prev; 
            current.prev = current.next; 
            current.next = temp; 
            current = current.prev; 
        } 
  
        /* Before changing head, check for the cases like empty  
         list and list with only one node */
        if (temp != null) { 
            head = temp.prev; 
        } 
    } 

n!/((n-k)!k!)