> This often trips up people who don't know how big O works They didn't ask for an algorithm with linear complexity. They explicitly asked for a solution "in o

> This often trips up people who don't know how big O works They didn't ask for an algorithm with linear complexity. They explicitly asked for a solution "in one pass". That's highly misleading. Edit (after the reply by zamalek): And you are perfectly right about the performance: it's probably slower than just doing two passes (one to find the length, the second to find the middle).