I've passed many algorithm interviews without knowing the answer beforehand. It's very possible, people just don't bother to learn. Any good textbook on algorit

I've passed many algorithm interviews without knowing the answer beforehand. It's very possible, people just don't bother to learn. Any good textbook on algorithms will give you the tools to create new ones. Mostly it's application of a few basic concepts, like big-O complexity, divide and conquer, or dynamic programming. Go through 100 problems on Project Euler and this stuff will become second nature.