队列：击鼓传花；双端队列：回文检查

下文用到的队列和双端队列类实现：队列和双端队列类

击鼓传花：循环队列

hotPotato(elementsList, num) {
  const queue = new Queue();
  const elimitatedList = [];

  for (let i = 0; i < elementsList.length; i++) {
    queue.enqueue(elementsList[i]);
  }

  while (queue.size() > 1) {
    for (let i = 0; i < num; i++) {
      queue.enqueue(queue.dequeue());
    }
    elimitatedList.push(queue.dequeue());
  }

  return {
    eliminated: elimitatedList,
    winner: queue.dequeue(),
    queue: queue
  };
}

回文检查：双端队列

palindromeChecker(aString) {
  if (
    aString === undefined ||
    aString === null ||
    (aString !== null && aString.length === 0)
  ) {
    return false;
  }
  const deque = new Deque();
  const lowerString = aString.toLocaleLowerCase().split(' ').join('');
  let firstChar;
  let lastChar;

  for (let i = 0; i < lowerString.length; i++) {
    deque.addBack(lowerString.charAt(i));
  }

  while (deque.size() > 1) {
    firstChar = deque.removeFront();
    lastChar = deque.removeBack();
    if (firstChar !== lastChar) {
      return false;
    }
  }

  return true;
}