export declare class Node<Item> {
    item: Item;
    next: Node<Item>;
}
/**
 *  The `Queue` class represents a first-in-first-out (FIFO)
 *  queue of generic items.
 *  It supports the usual <em>enqueue</em> and <em>dequeue</em>
 *  operations, along with methods for peeking at the first item,
 *  testing if the queue is empty, and iterating through
 *  the items in FIFO order.
 *  <p>
 *  This implementation uses a singly linked list with a static nested class for
 *  linked-list nodes. See {@link LinkedQueue} for the version from the
 *  textbook that uses a non-static nested class.
 *  See {@link ResizingArrayQueue} for a version that uses a resizing array.
 *  The <em>enqueue</em>, <em>dequeue</em>, <em>peek</em>, <em>size</em>, and <em>is-empty</em>
 *  operations all take constant time in the worst case.
 *  <p>
 *  For additional documentation, see <a href="https://algs4.cs.princeton.edu/13stacks">Section 1.3</a> of
 *  <i>Algorithms, 4th Edition</i> by Robert Sedgewick and Kevin Wayne.
 *
 *  @param <Item> the generic type of an item in this queue
 */
export default class Queue<Item> implements Iterable<Item> {
    private first;
    private last;
    private n;
    private modCount;
    constructor();
    /**
     * Returns true if this queue is empty.
     *
     * @return  `true` if this queue is empty; `false` otherwise
     */
    isEmpty(): boolean;
    /**
     * Returns the number of items in this queue.
     *
     * @return the number of items in this queue
     */
    size(): number;
    /**
     * Returns the item least recently added to this queue.
     *
     * @return the item least recently added to this queue
     * @throws Error if this queue is empty
     */
    peek(): Item;
    /**
     * Adds the item to this queue.
     *
     * @param tem the item to add
     */
    enqueue(item: Item): void;
    /**
     * Removes and returns the item on this queue that was least recently added.
     *
     * @return the item on this queue that was least recently added
     * @throws Error if this queue is empty
     */
    dequeue(): Item;
    /**
     * Returns a string representation of this queue.
     *
     * @return the sequence of items in FIFO order, separated by spaces
     */
    toString(): string;
    /**
     * Returns an iterator that iterates over the items in this queue in FIFO order.
     *
     * @return an iterator that iterates over the items in this queue in FIFO order
     */
    [Symbol.iterator](): {
        next(): IteratorResult<Item, any>;
    };
}