Books

Introduction to Algorithms
Thomas H. Cormen
technicalcomputer-science
CLRS, after its four authors, and the standard algorithms text in most computer science departments for thirty years. It is a reference rather than a book you read through: rigorous, proof-led, and deliberately language-agnostic — the pseudocode belongs to no compiler.
It is also enormous. Almost nobody has read all of it, which the authors have more or less acknowledged.