4 ms·

I kept scrolling, hoping to see "serialize a binary tree" or something I could answer. Disappointed.

• sanbor 7y ago
  That would be easy. Invert the binary tree it's the tricky one.
  • rvz 7y ago
    > Invert the binary tree it's the tricky one. This is too easy for everyone in this thread. Try this: Mathematically prove that the time complexity of the DFS algorithm is O(V+E).