July 04, 2022 |6.3K Views

    Reversing the first K elements of a Queue

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    Given an integer k and a queue of integers, we need to reverse the order of the first k elements of the queue, leaving the other elements in the same relative order.
    Only following standard operations are allowed on queue.

    enqueue(x) : Add an item x to rear of queue
    dequeue() : Remove an item from front of queue
    size() : Returns number of elements in queue.
    front() : Finds front item.

    Follow the below steps to implement the idea:

    Create an empty stack.
    One by one dequeue first K items from given queue and push the dequeued items to stack.
    Enqueue the contents of stack at the back of the queue
    Dequeue (size-k) elements from the front and enqueue them one by one to the same queue.
     


    Reversing the first K elements of a Queue : https://www.geeksforgeeks.org/reversing-first-k-elements-queue/