import { Comparator } from './utils/comparator';

export declare class Heap<T = number> {
    private _heap;
    private _comparator;
    /**
     * Creates a new instance of Heap.
     *
     * @param comparator The comparator function to use. (Optional)
     */
    constructor(comparator?: Comparator<T>);
    /**
     * Returns the number of elements in the heap.
     *
     * @timeComplexity `O(1)`
     */
    size(): number;
    /**
     * Returns true if the heap is empty, false otherwise.
     *
     * @timeComplexity `O(1)`
     */
    isEmpty(): boolean;
    /**
     * Returns the top element of the heap without removing it.
     *
     * @timeComplexity `O(1)`
     *
     * @returns Returns the top element of the heap or undefined if
     * the heap is empty.
     */
    peek(): T | void;
    /**
     * Adds elements to the heap.
     *
     * @timeComplexity `O(k * log(n))` where `k` is the number of items to add.
     *
     * @param items The elements to add to the heap.
     */
    push(...items: T[]): void;
    /**
     * Removes the top element from the heap and returns it.
     *
     * @timeComplexity `O(log(n))`
     *
     * @returns The top element of the heap or undefined if
     * the heap is empty.
     */
    pop(): T | undefined;
    /**
     * Clears the heap.
     *
     * @timeComplexity `O(1)`
     */
    clear(): void;
    /**
     * Clones the heap.
     *
     * @timeComplexity `O(n)`
     */
    clone(): Heap<T>;
    /**
     * Converts the heap to a sorted array.
     *
     * @timeComplexity `O(n * log(n))`
     */
    toArray(): T[];
    /**
     * Builds a heap from the given array.
     *
     * @param array The array to build the heap from.
     * @param comparator The comparator function to use. (Optional)
     *
     * @timeComplexity `O(n * log(n))`
     *
     * @returns The heap built from the given array.
     */
    static fromArray<T>(array: T[], comparator?: Comparator<T>): Heap<T>;
    /**
     * Moves the element at the given index down the heap to its
     * correct position.
     *
     * @param index The index of the element to move down.
     */
    private _heapifyDown;
    /**
     * Moves the element at the given index up the heap to its correct position.
     *
     * @param index The index of the element to move up.
     */
    private _heapifyUp;
    private _getParentIndex;
    private _getLeftChildIndex;
    private _getRightChildIndex;
}