/**
 * Implements a "round-robin" Stack ("first-in last-out" aka FILO) with a limited size.
 * Like an array of a fixed size. When it runs out of space - it starts writing on top of itself
 * from index 0.
 *
 *
 */
export declare class Stack<T> {
    readonly size: number;
    constructor(size: number);
    /**
     * Index of a slot to get written TO next.
     * Currently this slot contains OLDEST item (if any).
     */
    private nextIndex;
    readonly items: T[];
    push(item: T): this;
    /**
     * Fill (overwrite) the whole Stack (all its items) with the passed `item`.
     */
    fill(item: T): this;
    /**
     * Returns last items in the right order.
     * Unlike raw `items` property that returns "items buffer" as-is (not ordered properly).
     */
    get itemsOrdered(): T[];
}
/**
 * Fixed-size FILO stack of Numbers.
 * Has convenience stat methods, e.g percentile, avg, etc.
 */
export declare class NumberStack extends Stack<number> {
    avg(): number;
    /**
     * Returns null if Stack is empty.
     */
    avgOrNull(): number | null;
    median(): number;
    medianOrNull(): number | null;
    /**
     * `pc` is a number from 0 to 100 inclusive.
     */
    percentile(pc: number): number;
    /**
     * `pc` is a number from 0 to 100 inclusive.
     * Returns null if Stack is empty.
     */
    percentileOrNull(pc: number): number | null;
    percentiles(pcs: number[]): Record<number, number>;
}