const swap = (arr: any[], i: number, j: number) => {
  [arr[i], arr[j]] = [arr[j], arr[i]];
  return arr;
};

export const fischerYates = (arr: any[], n?: number) => {
  n = n || arr.length;
  arr = [...arr];
  const r: any[] = [];
  while (r.length < n) {
    swap(arr, 0, Math.floor(Math.random() * arr.length));
    r.push(arr.shift());
  }
  return r;
};