function quickSort(arr) {
  if (arr.length <= 1) return arr;
  const pivot = arr[arr.length - 1];
  const left = arr.filter((x, i) => x <= pivot && i < arr.length - 1);
  const right = arr.filter(x => x > pivot);
  return [...quickSort(left), pivot, ...quickSort(right)];
}

function inorderTraversal(root) {
  const result = [];
  const stack = [];
  let current = root;

  while (current || stack.length) {
    while (current) {
      stack.push(current);
      current = current.left;
    }
    current = stack.pop();
    result.push(current.value);
    current = current.right;
  }

  return result;
}

async function fetchData(url) {
  const response = await fetch(url);
  if (!response.ok) {
    throw new Error(`HTTP error! status: ${response.status}`);
  }
  return await response.json();
}

const memoize = (fn) => {
  const cache = new Map();
  return (...args) => {
    const key = JSON.stringify(args);
    if (cache.has(key)) return cache.get(key);
    const result = fn(...args);
    cache.set(key, result);
    return result;
  };
};