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Time Complexity · #17 · 2026-04-21

What's the Big-O?

JavaScript ·Difficulty 3/3

How to play

Read the code and pick its time complexity from four Big-O choices. Think about loops, recursion, and hidden costs. Press 1–4 or click to answer.

Binary tree with n nodes. What is the time complexity?

function inorder(node) {
  if (!node) return [];
  return [
    ...inorder(node.left),
    node.val,
    ...inorder(node.right)
  ];
}

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Press 1 through 4, or tap a numbered choice, to answer. Back to hub