/**
 * Stores a collection of objects in such a way that the highest priority element is always at front.
 *
 * The element type `T` can has method `compare(a, b)` and/or method `valueOf()`.
 */
export declare class BinaryHeap<T> {
    private readonly compare;
    private content;
    /**
     * @param compareFn - Function to compare the priority of `a` and `b`. Returns positive if `a` has higher
     *                    priority than `b`; returns negitave if `b` has higer priority than `a`.
     *                    If this parameter is omitted, use `T.compare()` if exist,
     *                    otherwise native number/string comparation.
     */
    constructor(compareFn?: (a: T, b: T) => number);
    /**
     * Adds an element into the collection and return the new size of the collection.
     */
    enqueue(element: T): number;
    /**
     * Alias of `enqueue`
     */
    push(element: T): number;
    /**
     * Returns the element at the front of the collection and removes it from the collection.
     */
    dequeue(): T | undefined;
    /**
     * Alias of `dequeue`
     */
    pop(): T | undefined;
    /**
     * Remove the element at the end of the collection and retures it.
     *
     * Note: heap is not sorted, the element at the end may not be the lowest priority.
     */
    pollLast(): T | undefined;
    /**
     * Returns the element at the front of the collection without removing it.
     */
    peek(): T | undefined;
    readonly size: number;
    /**
     * Removes all elements from the collection.
     */
    clear(): void;
    /**
     * Brings a value up until its parent is greater than it.
     */
    private float;
    /**
     * Moves a value downward until it is greater than its children.
     */
    private sink;
}