dir01

const flatten = <T>(arr: T[][]): T[] => ([] as T[]).concat(...arr);

test("flatten", () => {
  expect(flatten([[1], [2], [3, 4]])).toEqual([1, 2, 3, 4]);
});

dir01

FROM node:10.14
RUN mkdir /app
WORKDIR /app
RUN npm install mongodb-memory-server@5.1.1
COPY ./index.js .
CMD node ./index.js

dir01

class CircularQueue {
  constructor(size) {
    this.size = size;
    this.storage = Array.from(new Array(size));
    Object.seal(this.storage);
    this.head = -1;
    this.tail = -1;
  }

  queue(value) {