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"Introduction to Algorithms" by Ronald Rivest is the standard college level textbook for this topic. I highly suggest starting there. For my undergraduate degree, this was meant to be taught in the first half of the second year and there's no specific mathematical requirements other than understanding advanced notation.
"Cracking the coding interview" will likely expose you to questions you'll see again during the interview process, but it lacks the formality.and structure of a mathematics text.