[sudeepj]

My bad. I based on the tweet from the author himself [1]

May be he meant to use "invert binary tree" as a representative example of questions that typically asked.

[1] https://twitter.com/mxcl/status/608682016205344768?lang=en

[eru]

No worries.

See https://news.ycombinator.com/item?id=27927159 for some more.

> May be he meant to use "invert binary tree" as a representative example of questions that typically asked.

Yes, that's a charitable and believable interpretation of his tweet.

(Though I don't know where he got that 90% figure from. Probably made up, like 85.12% of statistics.)

[6gvONxR4sf7o]

It’s a charitable interpretation, but seems super reasonable. Around that time, I think “inverting a binary tree” was a bit of a meme/shorthand about software interviewing.